ここではバレーボール経験者、未経験者に関わらずバレーボールがどんなものか知ってもらえるようにしていきたいと思います。
できる限り画像や映像を交えて更新していきたいと思います！
手のひらを外に向けて額の前でボールを軽くはじくように(厳密にはキャッチ＆リリース)して行うパス。オーバーパスともいいます。
緩やかな速さのボールを、頭の上方で、両手でボールを軽く押し上げるような姿勢でボールを弾くプレイ。コントロールを重視する次のアタックの前に行うことが多い。
Pass(underarm,bump)
Also called reception, the pass is the attempt by a team to properly handle the opponent's serve, or any form of attack. Proper handling includes not only preventing the ball from touching the court, but also making it reach the position where the setter is standing quickly and precisely.
The skill of passing involves fundamentally two specific techniques: underarm pass, or bump, where the ball touches the inside part of the joined forearms or platform, at waist line; and overhand pass, where it is handled with the fingertips, like a set, above the head. Either are acceptable in professional and beach volleyball, however there are much tighter regulations on the overhand pass in beach volleyball.
ひじを伸ばして両手を組み、ひじから手首までの部分を使ってボールを送り出すパス。アンダーパスとも言います。
相手からの強い返球を低い位置で受けるときに効果的なプレイ。そのためレシーブと 呼ばれることもあり、大別してサービスレシーブとスパイクレシーブの2種類がある。とりわけスパイクレシーブをディグ（Dig）と呼ぶ。両腕を体の正面に 伸ばして、片手でもう一方の手を軽く握り、手首の付近でボールを弾く動作がよく用いられる。低い位置のボールを受けるには都合が良い。その反面、ボールの コントロールは比較的難しい。
Pass(underarm,bump)
Also called reception, the pass is the attempt by a team to properly handle the opponent's serve, or any form of attack. Proper handling includes not only preventing the ball from touching the court, but also making it reach the position where the setter is standing quickly and precisely.
The skill of passing involves fundamentally two specific techniques: underarm pass, or bump, where the ball touches the inside part of the joined forearms or platform, at waist line; and overhand pass, where it is handled with the fingertips, like a set, above the head. Either are acceptable in professional and beach volleyball, however there are much tighter regulations on the overhand pass in beach volleyball.
サーブには、手を下から振り出すアンダーハンドサーブ、ボールを高く上げてジャンプしながら強く打つスパイクサーブ（ジャンプサーブ）、
ジャンプしないでコントロール重視で打つフローターサーブ、助走をつけて軽くジャンプしその後トスを上げて打つブロードサーブ、
ジャンプしてフローターの動作で打つジャンプフローターサーブ、アンダーハンドで高く打ち上げる天井サーブなどの方法がある。
Serve
A player stands behind the inline and serves the ball, in an attempt to drive it into the opponent's court. His or her main objective is to make it land inside the court; it is also desirable to set the ball's direction, speed and acceleration so that it becomes difficult for the receiver to handle it properly. A serve is called an "ace" when the ball lands directly onto the court or travels outside the court after being touched by an opponent.
In contemporary volleyball, many types of serves are employed:
Underhand: a serve in which the player strikes the ball below the waist instead of tossing it up and striking it with an overhand throwing motion. Underhand serves are considered very easy to receive and are rarely employed in high-level competitions.
Sky ball serve: a specific type of underhand serve occasionally used in beach volleyball, where the ball is hit so high it comes down almost in a straight line. This serve was invented and employed almost exclusively by the Brazilian team in the early 1980s and is now considered outdated. In Brazil, this serve is called Jornada nas Estrelas .
Topspin: an overhand serve where the player tosses the ball high and hits it with a wrist span, giving it topspin which causes it to drop faster than it would otherwise and helps maintain a straight flight path. Topspin serves are generally hit hard and aimed at a specific returner or part of the court. Standing topspin serves are rarely used above the high school level of play.
Float: an overhand serve where the ball is hit with no spin so that its path becomes unpredictable, akin to a knukleball in baseball.
Jump serve: an overhand serve where the ball is first tossed high in the air, then the player makes a timed approach and jumps to make contact with the ball, hitting it with much pace and topspin. This is the most popular serve amongst college and professional teams.
Jump float: an overhand serve where the ball is tossed high enough that the player may jump before hitting it similarly to a standing float serve. The ball is tossed lower than a topspin jump serve, but contact is still made while in the air. This serve is becoming more popular amongst college and professional players because it has a certain unpredictability in its flight pattern.
セットは通常は２回目にボールに触る行為になることが多い。
セットの目的としてはアタッカーがスパイクを打ちやすいように各ポジションのアタッカーの前方（通常ネットから０．５～１ｍ程度の位置）に
ボールをオーバーパスを用いてトスアップすることである。
The set is usually the second contact that a team makes with the ball. The main goal of setting is to put the ball in the air in such a way that it can be driven by an attack into the opponent's court. The setter coordinates the offensive movements of a team, and is the player who ultimately decides which player will actually attack the ball.
As with passing, one may distinguish between an overhand and a bump set. Since the former allows for more control over the speed and direction of the ball, the bump is used only when the ball is so low it cannot be properly handled with fingertips, or in beach volleyball where rules regulating overhand setting are more stringent. In the case of a set, one also speaks of a front or back set, meaning whether the ball is passed in the direction the setter is facing or behind the setter. There is also a jump set that is used when the ball is too close to the net. In this case the setter usually jumps off his or her right foot straight up to avoid going into the net. The setter usually stands about ⅔ of the way from the left to the right of the net and faces the left (the larger portion of net that he or she can see).
Sometimes a setter refrains from raising the ball for a teammate to perform an attack and tries to play it directly onto the opponent's court. This movement is called a "dump".This can only be performed when the setter is in the front row, otherwise it constitutes an illegal back court attack. The most common dumps are to 'throw' the ball behind the setter or in front of the setter to zones 2 and 4. More experienced setters toss the ball into the deep corners or spike the ball on the second hit.
跳躍しながらネット越しにボールを打つ動作がスパイクである。相手コートに叩き付けるように下向きに打つことが基本だが、相手のブロックにボールをわざと当ててコート外にボールを出したり、タイミングをずらして相手のブロックを避けてプレイする場合もある。
Attack
The attack, also known as the spike, is usually the third contact a team makes with the ball. The object of attacking is to handle the ball so that it lands on the opponent's court and cannot be defended. A player makes a series of steps (the "approach"), jumps, and swings at the ball.
Ideally the contact with the ball is made at the apex of the hitter's jump. At the moment of contact, the hitter's arm is fully extended above his or her head and slightly forward, making the highest possible contact while maintaining the ability to deliver a powerful hit. The hitter uses arm swing, wrist snap, and a rapid forward contraction of the entire body to drive the ball. A 'bounce' is a slang term for a very hard/loud spike that follows an almost straight trajectory steeply downward into the opponent's court and bounces very high into the air. A "kill" is the slang term for an attack that is not returned by the other team thus resulting in a point.
Contemporary volleyball comprises a number of attacking techniques:
Backcourt (or backrow)/pipe attack: an attack performed by a back row player. The player must jump from behind the 3-meter line before making contact with the ball, but may land in front of the 3-meter line.
Line and Cross-court Shot: refers to whether the ball flies in a straight trajectory parallel to the side lines, or crosses through the court in an angle. A cross-court shot with a very pronounced angle, resulting in the ball landing near the 3-meter line, is called a cut shot.
Dip/Dink/Tip/Cheat/Dump: the player does not try to make a hit, but touches the ball lightly, so that it lands on an area of the opponent's court that is not being covered by the defense.
Tool/Wipe/Block-abuse: the player does not try to make a hard spike, but hits the ball so that it touches the opponent's block and then bounces off-court.
Off-speed hit: the player does not hit the ball hard, reducing its speed and thus confusing the opponent's defense.
Quick hit/"One": an attack (usually by the middle blocker) where the approach and jump begin before the setter contacts the ball. The set (called a "quick set") is placed only slightly above the net and the ball is struck by the hitter almost immediately after leaving the setter's hands. Quick attacks are often effective because they isolate the middle blocker to be the only blocker on the hit.
Slide: a variation of the quick hit that uses a low back set. The middle hitter steps around the setter and hits from behind him or her.
Double quick hit/"Stack"/"Tandem": a variation of quick hit where two hitters, one in front and one behind the setter or both in front of the setter, jump to perform a quick hit at the same time. It can be used to deceive opposite blockers and free a fourth hitter attacking from backcourt, maybe without block at all.
相手のスパイクに対してタイミングよくジャンプし、両手を上に伸ばして自分のコートにボールが打ち込まれることを防ぐ、またはその威力を軽減させるプレイ。3回で相手コートに返球することになっているが、ブロックはそのうちの1回には数えない。
Block
Blocking refers to the actions taken by players standing at the net to stop or alter an opponent's attack.
A block that is aimed at completely stopping an attack, thus making the ball remain in the opponent's court, is called offensive. A well-executed offensive block is performed by jumping and reaching to penetrate with one's arms and hands over the net and into the opponent's area. It requires anticipating the direction the ball will go once the attack takes place. It may also require calculating the best foot work to executing the "perfect" block.
The jump should be timed so as to intercept the ball's trajectory prior to it crossing over the net. Palms are held deflected downward about 45–60 degrees toward the interior of the opponents court. A "roof" is a spectacular offensive block that redirects the power and speed of the attack straight down to the attacker's floor, as if the attacker hit the ball into the underside of a peaked house roof.
By contrast, it is called a defensive, or "soft" block if the goal is to control and deflect the hard-driven ball up so that it slows down and becomes more easy to be defended. A well-executed soft-block is performed by jumping and placing one's hands above the net with no penetration into the opponent's court and with the palms up and fingers pointing backward.
Blocking is also classified according to the number of players involved. Thus, one may speak of single (or solo), double, or triple block.
Successful blocking does not always result in a "roof" and many times does not even touch the ball. While it's obvious that a block was a success when the attacker is roofed, a block that consistently forces the attacker away from his or her 'power' or preferred attack into a more easily controlled shot by the defense is also a highly successful block.
At the same time, the block position influences the positions where other defenders place themselves while opponent hitters are spiking.
Formations
The three standard volleyball formations are known as "4–2", "6–2" and "5–1", which refers to the number of hitters and setters respectively. 4–2 is a basic formation used only in beginners' play, while 5–1 is by far the most common formation in high-level play.
The 4–2 formation has four hitters and two setters. The setters usually set from the middle front or right front position. The team will therefore have two front-row attackers at all times. In the international 4–2, the setters set from the right front position. The international 4–2 translates more easily into other forms of offense.
The setters line up opposite each other in the rotation. The typical lineup has two outside hitters. By aligning like positions opposite themselves in the rotation, there will always be one of each position in the front and back rows. After service, the players in the front row move into their assigned positions, so that the setter is always in middle front. Alternatively, the setter moves into the right front and has both a middle and an outside attacker; the disadvantage here lies in the lack of an offside hitter, allowing one of the other team's blockers to "cheat in" on a middle block.
The clear disadvantage to this offensive formation is that there are only two attackers, leaving a team with fewer offensive weapons.
Another aspect is to see the setter as an attacking force, albeit a weakened force, because when the setter is in the front court they are able to 'tip' or 'dump', so when the ball is close to the net on the second touch, the setter may opt to hit the ball over with one hand. This means that the blocker who would otherwise not have to block the setter is engaged and may allow one of the hitters to have an easier attack.
In the 6–2 formation, a player always comes forward from the back row to set. The three front row players are all in attacking positions. Thus, all six players act as hitters at one time or another, while two can act as setters. So the 6–2 formation is actually a 4–2 system, but the back-row setter penetrates to set.
The 6–2 lineup thus requires two setters, who line up opposite to each other in the rotation. In addition to the setters, a typical lineup will have two middle hitters and two outside hitters. By aligning like positions opposite themselves in the rotation, there will always be one of each position in the front and back rows. After service, the players in the front row move into their assigned positions.
The advantage of the 6–2 is that there are always three front-row hitters available, maximizing the offensive possibilities. However, not only does the 6–2 require a team to possess two people capable of performing the highly specialized role of setter, it also requires both of those players to be effective offensive hitters when not in the setter position. At the international level, only the Cuban National Women's Team employs this kind of formation. It is also used in Women's NCAA play, partially due to the variant rules used which allow 12 substitutions per set (as opposed to the 6 allowed in the standard rules).
The 5–1 formation has only one player who assumes setting responsibilities regardless of his or her position in the rotation. The team will therefore have three front-row attackers when the setter is in the back row, and only two when the setter is in the front row, for a total of five possible attackers.
The player opposite the setter in a 5–1 rotation is called the opposite hitter. In general, opposite hitters do not pass; they stand behind their teammates when the opponent is serving. The opposite hitter may be used as a third attack option (back-row attack) when the setter is in the front row: this is the normal option used to increase the attack capabilities of modern volleyball teams. Normally the opposite hitter is the most technical skilled hitter of the team. Back-row attacks generally come from the back-right position, known as zone 1, but are increasingly performed from back-center in high-level play.
The big advantage of this system is that the setter always has 3 hitters to vary sets with. If the setter does this well, the opponent's middle blocker may not have enough time to block with the outside blocker, increasing the chance for the attacking team to make a point.
There is another advantage, the same as that of a 4–2 formation: when the setter is a front-row player, he or she is allowed to jump and "dump" the ball onto the opponent's side. This too can confuse the opponent's blocking players: the setter can jump and dump or can set to one of the hitters. A good setter knows this and thus won't only jump to dump or to set for a quick hit, but when setting outside as well to confuse the opponent.
The 5–1 offense is actually a mix of 6–2 and 4–2: when the setter is in the front row, the offense looks like a 4–2; when the setter is in the back row, the offense looks like a 6–2.
6人制のルールは国際バレーボール連盟が、9人制のルールは日本バレーボール協会が定めている。
ここではおもに6人制のルールについて記述する。
長辺18m、短辺9mの長方形のラインが引かれたコートを用いる。その中央にはコートを二分する形で幅1m、長さ約10mのネットが張られている。 ネットの高さは男子が2.43m、女子が2.24mと定められている。ネットからそれぞれ3mにはアタックラインと呼ばれるラインがある。
コートの外には3m以上の空間（フリーゾーン）、天井までの高さは7m以上が必要とされる。国際バレーボール連盟および日本バレーボール協会主催の 競技会では、フリーゾーンは最小限サイドラインから5m、エンドラインから8m、天井の高さは12.5m必要と定められている。
ボール
色は均一で明るい色か、複数色の組み合わせとされるが、大会や試合では同一でなくてはいけない。円周は65-67cm、重量は260-280g、内圧は0.30-0.325kgf/cm2。現在、全国大会の取り扱いでは、0.31kgf/cm2に統一することとなっている。
ユニフォーム
ジャージ、パンツ、ソックスはリベロ以外の全員がそろっていることが条件。リベロ・プレーヤーは対照的な色のユニフォームでないといけない。ユニ フォームのナンバーは1から18番を原則としているが、やむをえない事情があれば、1から99番まで使用することができる。数字の大きさは胸部が15cm 以上、背部は20cm以上、字幅は2cm以上でなければならない。チームキャプテンは、胸のナンバーの下に長さ8cm、幅2cmのマークをつける。
1チームは、6人以上12人以内のプレーヤー、監督1人、コーチ1人、トレーナー1人、医師1人で構成される。前衛・後衛それぞれ3人、計6人で競 技を行う。プレーヤーのうち1人をリベロプレーヤーとして登録することができる（中体連・高体連主催の大会では、2名まで登録できる）。
但し、国内大会の競技要項により、部長、マネージャーなどがベンチスタッフとして認められることがある。 現在、全国大会やそれに準じる大会では、監督を含むベンチスタッフを置くには、コーチや指導者としての公認資格の有資格者がいることを条件としている。
国際バレーボール連盟および日本バレーボール協会主催のシニア競技会においては最大限14名のプレーヤーで構成できる。この場合、リベロを除くプレーヤーは最大限12名登録できる。
リベロを除く上記プレーヤーの内、1名がチームキャプテンとなり、試合中コート内でプレーしている間はゲームキャプテンとして行動する。チームキャ プテンがコート外にいる時は他のコート上のプレーヤーがゲームキャプテンとなる。ゲームキャプテンは試合中断中のとき、競技規則の適用などについて審判員 に説明を求めることができる。ゲームキャプテンは監督不在の時、タイムアウトや選手交代の権限を持つ。
試合はラリーポイント制で行われ、国内の主な大会、国際試合は5セットマッチで行われる。それ以外の大会では3セットマッチが採用されることがある。
ラリーポイント制
サーブ権を持つチームの選手がサービスを行うことでボールの打ち合いが始まり、攻撃決定やミス、反則で打ち合いが終わる。これをラリーという。ラリーに勝ったチームが、１点を得ると同時に次のサーブ権を得る。
5セットマッチ
先 に25ポイント（第5セットに限り15ポイント）を取ったチームに1セットが与えられ、3セットを先に獲得したチームが勝者となる。ポイントが 24-24（第5セットは14-14）となった場合はデュースとなり、どちらかが先に2ポイントの差を付けるまでそのセットは続けられる。
3セットマッチ
先に25ポイントを取ったチームに1セットが与えられ、2セットを先に獲得したチームが勝者となる。ポイントが24-24となった場合はデュースとなり、どちらかが先に2ポイントの差を付けるまでそのセットは続けられる。
各チームは一回につき30秒間のタイムアウトをとることができる。各チームはこの間に作戦を練ったり、選手を休憩させるなどしている。タイムアウトの回数制限は両チームとも各セット2回ずつ。たとえ使わなくても、次のセットに持ち越すことはできない。
また、第5セット以外に両チームの内、8点と16点を先取した場合、自動的にプレイが止まる。これを「テクニカルタイムアウト」という。テクニカルタイムアウトの休憩時間は60秒間[2]であり、これにより第5セット以外の各セットに最低2回プレイが止まる。
チームはネットを越えてボールを返すために最大で3回（6人制の場合、正当なブロックは一回として数えない）ボールに触れることができる。第1回目 のレシーブやブロックの場合を除き、競技者は連続して2回ボールを打つことはできない。現行のルールではボールを返す際に体のどの部位を用いてもよい。
各プレーヤーはそれぞれ次に示すポジションに就く。
前衛（ネットに近い側）：左からフロントレフト(FL)、フロントセンター(FC)、フロントライト(FR)
後衛（ネットから遠い側）：左からバックレフト(BL)、バックセンター(BC)、バックライト(BR)
後衛のプレーヤーはネット際でのスパイクやブロックを禁止されるなど、 ポジションに応じてプレーに制限がある。
ポジションはサーブ権を獲得するごとに時計回りに入れ替わり（これをローテーションという）、新たにバックライトに就くことになったプレーヤーがサーブを打つ。 ローテーションの順序は、 バックライト→バックセンター→バックレフト→フロントレフト→フロントセンター→フロントライト の順。
また、後衛のプレーヤーと何度でも交替できる選手リベロプレーヤーを 置くことができる。 リベロプレーヤーは、 後衛のプレーヤーと交代してコートに入り、 ローテーションが進行して前衛にまわる前に元のプレーヤーと交代してゲームを離れる。 リベロプレーヤーの交代は、 ラリー中以外のときに 特にゲームを中断せずに行われる。 リベロプレーヤーには、後衛に課せられるプレー上の制限に加えて フロントゾーンでのトスや、ネットよりも上方でボールに触れて相手コートに返球することも禁止される。 リベロプレーヤーは 他のプレーヤーと異なる色のユニフォームを着用する。
ダブル・コンタクト（ドリブル）
同じプレーヤーが連続してボールに触れた場合。ブロックと1回目のレシーブは除く。
キャッチボール（ホールディング）
ボールがプレーヤーの身体の一部で静止してしまった場合。通称ホール。
ボール・アウト
ボールがコート外に落ちたり、サイドマーカー（通称アンテナ、ネット付近でのコートの内外を示すネットに取り付ける棒）に触れたりその外側を通過して相手側コートに返った場合。
タッチ・ネット
ボールを直接プレーしようとした動作中、または、そのプレーの一部であったときにネットの上部白帯やアンテナに触れた場合。通称ネッチ。
ペネトレーション・フォールト（オーバーネット）
ネットを越えて相手側のコートにあるボールに触れた場合。自コート側に帰ってくることが確実なボールは除く。
フォア・ヒット（オーバータイムス）
自コートから相手コートに返球する間に4回以上ボールに触れた場合。ブロックは1回には数えない。
インターフェア
相手側のコートにあるボールに意図的に触れた場合や相手選手のプレーを妨害した場合。
ペネトレーション・フォールト（パッシング・ザ・センターライン）
プレーヤーがセンターラインを越して相手側のコートに入った場合。センターラインから踏み出なければ反則にならない。
ポジショナル・フォールト（アウト・オブ・ポジション、ローテーションミス）
サーブを打つ瞬間にプレーヤーが規定のポジションに就いていない場合。リベロ・プレーヤーの交代が正当でない場合にも適用される。
アタック・ヒットの反則
バック・プレーヤーがフロント・ゾーン（アタックラインの延長線上よりネットに近い区域も含む）から跳び上がってネット上端より完全に高い位置のボールを相手コートへ返球した場合。
アシステッド・ヒット
プレーヤーが味方の他プレーヤーや外部の構造物などの助けを借りてボールをプレイした場合。
サーブに関する反則
1. 主審がサーブの許可を出したあと、8秒以内にサーブを打たなかった場合（ディレイ・イン・サービス いわゆる8秒ルール違反）。
2. サーブ順を間違えた場合。
3. サーブエリア外またはエンドラインを踏み越してサーブした場合。
4. 味方プレーヤーがネット際でスクリーンを形成して、そのブラインドにサーブを打った場合。
9人制では、6人制と比較して、次のような違いがある。
一般男子はコートがやや広い。
ネットの高さがやや低い。
ボールはママさんバレーは白色とカラーボール（全国大会のみ白一色）、一般は6人制と同じ（6人制はカラーボール）
交代要員は3人以内（6人制では6人以内）。
3セットマッチ、21ポイントで1セット。
アタックライン、リベロ、ローテーションが無い。
プレー中、ネットにボールが触れた場合には、4打以内に相手コートに返せばよい。
サーブの打ち直しが1回に限り可能。
ブロックを1打に数える（6人制では1打に含まない）。
どの選手もスパイクを打てる（6人制では後衛の選手はアタックラインを越えてスパイクを打てないが9人制にアタックラインは無い）。
オーバーネットしない限り、サーブブロック（スパイクでも可）が有効（6人制では反則）。
Rules of the game
The court
The game is played on a volleyball court 18 meters (59 feet) long and 9 meters (29.5 feet) wide, divided into two 9 m × 9 m halves by a one-meter (40-inch) wide net placed so that the top of the net is 2.43 meters (7 feet 11 5/8 inches) above the center of the court for men's competition, and 2.24 meters (7 feet 4 1/8 inches) for women's competition (these heights are varied for veterans and junior competitions).
There is a line 3 meters from and parallel to the net in each team court which is considered the "attack line". This "3 meter" (or 10 foot) line divides the court into "back row" and "front row" areas (also back court and front court). These are in turn divided into 3 areas each: these are numbered as follows, starting from area "1", which is the position of the serving player:
After a team gains the serve (also known as siding out), its members must rotate in a clockwise direction, with the player previously in area "2" moving to area "1" and so on, with the player from area "1" moving to area "6".
The team courts are surrounded by an area called the free zone which is a minimum of 3 meters wide and which the players may enter and play within after the service of the ball. All lines denoting the boundaries of the team court and the attack zone are drawn or painted within the dimensions of the area and are therefore a part of the court or zone. If a ball comes in contact with the line, the ball is considered to be "in". An antenna is placed on each side of the net perpendicular to the sideline and is a vertical extension of the side boundary of the court. A ball passing over the net must pass completely between the antennae (or their theoretical extensions to the ceiling) without contacting them.
The ball
FIVB regulations state that the ball must be spherical, made of leather or synthetic leather, have a circumference of 65–67 cm, a weight of 260–280 g and an inside pressure of 0.30–0.325 kg/cm2. Other governing bodies have similar regulations.
Each team consists of six players. To get play started, a team is chosen to serve by coin toss. A player from the serving team throws the ball into the air and attempts to hit the ball so it passes over the net on a course such that it will land in the opposing team's court (the serve). The opposing team must use a combination of no more than three contacts with the volleyball to return the ball to the opponent's side of the net. These contacts usually consist first of the bump or pass so that the ball's trajectory is aimed towards the player designated as the setter; second of the set (usually an over-hand pass using wrists to push finger-tips at the ball) by the setter so that the ball's trajectory is aimed towards a spot where one of the players designated as an attacker can hit it, and third by the attacker who spikes (jumping, raising one arm above the head and hitting the ball so it will move quickly down to the ground on the opponent's court) to return the ball over the net. The team with possession of the ball that is trying to attack the ball as described is said to be on offense.
The team on defense attempts to prevent the attacker from directing the ball into their court: players at the net jump and reach above the top (and if possible, across the plane) of the net to block the attacked ball. If the ball is hit around, above, or through the block, the defensive players arranged in the rest of the court attempt to control the ball with a dig (usually a fore-arm pass of a hard-driven ball). After a successful dig, the team transitions to offense.
The game continues in this manner, rallying back and forth, until the ball touches the court within the boundaries or until an error is made. The most frequent errors that are made are either to fail to return the ball over the net within the allowed three touches, or to cause the ball to land outside the court. A ball is "in" if any part of it touches a sideline or end-line, and a strong spike may compress the ball enough when it lands that a ball which at first appears to be going out may actually be in. Players may travel well outside the court to play a ball that has gone over a sideline or end-line in the air.
Other common errors include a player touching the ball twice in succession, a player "catching" the ball, a player touching the net while attempting to play the ball, or a player penetrating under the net into the opponent's court. There are a large number of other errors specified in the rules, although most of them are infrequent occurrences. These errors include back-row or libero players spiking the ball or blocking (back-row players may spike the ball if they jump from behind the attack line), players not being in the correct position when the ball is served, attacking the serve in the front court and above the height of the net, using another player as a source of support to reach the ball, stepping over the back boundary line when serving, taking more than 8 seconds to serve,or playing the ball when it is above the opponent's court.
When the ball contacts the floor within the court boundaries or an error is made, the team that did not make the error is awarded a point, whether they served the ball or not. If the ball hits the line, the ball is counted as in. The team that won the point serves for the next point. If the team that won the point served in the previous point, the same player serves again. If the team that won the point did not serve the previous point, the players of the team rotate their position on the court in a clockwise manner. The game continues, with the first team to score 25 points (and be two points ahead) awarded the set. Matches are best-of-five sets and the fifth set (if necessary) is usually played to 15 points. (Scoring differs between leagues, tournaments, and levels; high schools sometimes play best-of-three to 25; in the NCAA games are played best-of-five to 25 as of the 2008 season.)
Before 1999, points could be scored only when a team had the serve (side-out scoring) and all sets went up to only 15 points. The FIVB changed the rules in 1999 (with the changes being compulsory in 2000) to use the current scoring system (formerly known as rally point system), primarily to make the length of the match more predictable and to make the game more spectator- and television-friendly.
In 1998 the libero player was introduced internationally.The libero is a player specialized in defensive skills: the libero must wear a contrasting jersey color from his or her teammates and cannot block or attack the ball when it is entirely above net height. When the ball is not in play, the libero can replace any back-row player, without prior notice to the officials. This replacement does not count against the substitution limit each team is allowed per set, although the libero may be replaced only by the player whom he or she replaced.
The libero may function as a setter only under certain restrictions. If she/he makes an overhand set, she/he must be standing behind (and not stepping on) the 3-meter line; otherwise, the ball cannot be attacked above the net in front of the 3-meter line. An underhand pass is allowed from any part of the court.
The libero is, generally, the most skilled defensive player on the team. There is also a libero tracking sheet, where the referees or officiating team must keep track of who the libero subs in and out for. There may only be one libero per set (game), although there may be a different libero in the beginning of any new set (game).
Furthermore, a libero is not allowed to serve, according to international rules, with the exception of the NCAA women's volleyball games, where a 2004 rule change allows the libero to serve, but only in a specific rotation. That is, the libero can only serve for one person, not for all of the people for whom he or she goes in. That rule change was also applied to high school and junior high play soon after.