This will discuss what combat entails in the D&D 3.5 setting. Please peruse and if you have any questions, please feel free to ask. There seems to be A LOT to the combat, but once you do it, it is pretty easy. It allows for many many many different options in combat than just walking up and swinging your sword.
Basics (See below for more details):
Combat in the D&D game is cyclical; everybody acts in turn in a regular cycle of rounds. Combat follows this sequence:
1. Each combatant starts out flat-footed. Once a combatant acts, he or she is no longer flat-footed.
2. The DM determines which characters are aware of their opponents at the start of the battle. If some but not all of the combatants are aware of their opponents, a surprise round happens before regular rounds of combat begin. The combatants who are aware of the opponents can act in the surprise round, so they roll for initiative. In initiative order (highest to lowest), combatants who started the battle aware of their opponents each take one action (either a standard action or a move action) during the surprise round. Combatants who were unaware do not get to act in the surprise round. If no one or everyone starts the battle aware, there is no surprise round.
3. Combatants who have not yet rolled initiative do so. All combatants are now ready to begin their first regular round of combat.
4. Combatants act in initiative order (highest to lowest) in what is called a "Round".
5. When everyone has had a turn, the combatant with the highest initiative acts again, and steps 4 and 5 repeat until combat ends.
Explanations of Processes above (Taken from various pages in the PHB 3.5 and edited here for ease of reading):
1. Each combatant starts out flat-footed. Once a combatant acts, he or she is no longer flat-footed.
flat-footed: Especially vulnerable to attacks at the beginning of a battle. Characters are flat-footed until their first turns in the initiative cycle. A flat-footed creature loses its Dexterity bonus to
Armor Class (if any) and cannot make attacks of opportunity.
2. The DM determines which characters are aware of their opponents at the start of the battle. If some but not all of the combatants are aware of their opponents, a surprise round happens before regular rounds of combat begin. The combatants who are aware of the opponents can act in the surprise round, so they roll for initiative. In initiative order (highest to lowest), combatants who started the battle aware of their opponents each take one action (either a standard action or a move action) during the surprise round. Combatants who were unaware do not get to act in the surprise round. If no one or everyone starts the battle aware, there is no surprise round.
Surprise is determined by the DM. Examples: A) Heavily armored characters wandering through a quiet underground labyrinth may be surprised by the kobolds who hear them and plan an ambush. B) The party of adventurers hear yelling as orcs in the next chamber are throwing bones. They burst in to surprise them.
3. Combatants who have not yet rolled initiative do so. All combatants are now ready to begin their first regular round of combat.
Initiative Checks: At the start of a battle, each combatant makes an initiative check (d20). An initiative check is a Dexterity check. Each character applies his or her Dexterity modifier to the roll. The DM finds out what order characters are acting in, counting down from highest result to lowest, and each character acts in turn. In every round that follows, the characters act in the same order (unless a
character takes an action that results in his or her initiative changing; see Special Initiative Actions, page 160). Usually, the DM writes the names of the characters down in initiative order so that
on subsequent rounds he can move quickly from one character to the next. If two or more combatants have the same initiative check result, the combatants who are tied act in order of total initiative
modifier (highest first). If there is still a tie, the tied characters should roll again to determine which one of them goes before the other.
Monster Initiative: Typically, the DM makes a single initiative checks for monsters and other opponents. That way, each player gets a turn each round and the DM also gets one turn. At the DM’s
option (I will be rolling for different groups), however, he can make separate initiative checks for different groups of monsters or even for individual creatures. For instance, the DM may make one initiative checks for an evil cleric of Nerull
and another check for all seven of her zombie guards.
Changing your Initiative Roll: You can change where you attack by doing one of the following:
Delay: By choosing to delay, you take no action and then act normally on whatever initiative count you decide to act. When you delay, you voluntarily reduce your own initiative result for the rest of the
combat. When your new, lower initiative count comes up later in the same round, you can act normally. You can specify this new initiative result or just wait until some time later in the round and act then, thus fixing your new initiative count at that point.
Delaying is useful if you need to see what your friends or opponents are going to do before deciding what to do yourself. The price you pay is lost initiative. You never get back the time you spend
waiting to see what’s going to happen. You can’t, however, interrupt anyone else’s action (as you can with a readied action).
Initiative Consequences of Delaying: Your initiative result becomes the count on which you took the delayed action. If you come to your next action and have not yet performed an action, you
don’t get to take a delayed action (though you can delay again). If you take a delayed action in the next round, before your regular turn comes up, your initiative count rises to that new point in the order
of battle, and you do not get your regular action that round.
Ready: The ready action lets you prepare to take an action later, after your turn is over but before your next one has begun. Readying is a standard action. It does not provoke an attack of opportunity (discussed below) (though the action that you ready might do so).
Readying an Action: You can ready a standard action, a move action, or a free action. To do so, specify the action you will take and the conditions under which you will take it. For example, you might
specify that you will shoot an arrow at anyone coming through a nearby doorway. Then, any time before your next action, you may take the readied action in response to that condition. The action occurs just before the action that triggers it. If the triggered action is part of another character’s activities, you interrupt the other character. Assuming he is still capable of doing so, he continues his
actions once you complete your readied action.
Your initiative result changes. For the rest of the encounter, your initiative result is the count on which you took the readied action, and you act immediately ahead of the character whose action
triggered your readied action.
You can take a 5-foot step as part of your readied action, but only if you don’t otherwise move any distance during the round. For instance, if you move up to an open door and then ready an action to
swing your sword at whatever comes near, you can’t take a 5-foot step along with the readied action (since you’ve already moved in this round).
Initiative Consequences of Readying: Your initiative result becomes the count on which you took the readied action. If you come to your next action and have not yet performed your readied
action, you don’t get to take the readied action (though you can ready the same action again). If you take your readied action in the next round, before your regular turn comes up, your initiative count
rises to that new point in the order of battle, and you do not get your regular action that round.
Distracting Spellcasters: You can ready an attack against a spellcaster with the trigger “if she starts casting a spell.” If you damage the spellcaster, she may lose the spell she was trying to cast (as determined by her Concentration check result).
Readying to Counterspell: You may ready a counterspell against a spellcaster (often with the trigger “if she starts casting a spell”). In this case, when the spellcaster starts a spell, you get a
chance to identify it with a Spellcraft check (DC 15 + spell level). If you do, and if you can cast that same spell (are able to cast it and have it prepared, if you prepare spells), you can cast the spell as a
counterspell and automatically ruin the other spellcaster’s spell. Counterspelling works even if one spell is divine and the other arcane.
A spellcaster can use dispel magic (page 223) to counterspell another spellcaster, but it doesn’t always work.
Readying a Weapon against a Charge: You can ready certain piercing weapons, setting them to receive charges (see Table 7–5: Weapons, page 116). A readied weapon of this type deals double
damage if you score a hit with it against a charging character.
4. Combatants act in initiative order (highest to lowest) in what is called a "Round".
Round: 6 seconds in the game world. At the table, a round presents an opportunity for each character involved in a combat situation to take an action. Anything a person could reasonably do in 6 seconds, your character can do in 1 round.
Movement: Movement is done in 5 foot squares.
Actions in Combat: 4 Types of Actions:
In a round you can do:
1-2 Free Actions +1 Move action + 1 Standard action OR
1-2 Free Actions + 2 Move actions OR
1-2 Free Actions + 1 Full-Round Action
1) Standard Action: A standard action allows you to do something. The most common type of standard action is an attack—a single melee or ranged attack. Other common standard actions including casting a spell, concentrating to maintain an active spell, activating a magic item, and using a special ability. See Table 8–2 (I'll have these tables added to this section for easy printing): Actions in Combat for other standard actions.
2) Move Action: A move action allows you to move your speed or perform an action that takes a similar amount of time. You can move your speed, climb one-quarter of your speed, draw or stow a weapon or other item, stand up, pick up an object, or perform some equivalent action (see Table 8–2: Actions in Combat (I'll have these tables added to this section for easy printing)). You can take a move action in place of a standard action. For instance, rather than moving your speed and attacking, you could stand up and move your speed (two move actions), put away a weapon and climb one-quarter of your speed (two move actions), or pick up an item and stow it in your backpack (two move actions).
If you move no actual distance in a round (commonly because you have swapped your move for one or more equivalent actions, such as standing up), you can take one 5-foot step either before,
during, or after the action. For example, if Tordek is on the ground, he can stand up (a move action), move 5 feet (a 5-foot step), and then attack.
3) Full-Round Action: A full-round action consumes all your effort during a round. The only movement you can take during a full-round action is a 5-foot step before, during, or after the action. You
can also perform free actions (see below) as your DM allows. The most common type of full-round action is a full attack, which allows you to make multiple melee or ranged attacks in a single round.
Some full-round actions do not allow you to take a 5-foot step. Some full-round actions can be taken as standard actions, but only in situations when you are limited to performing only a standard
action during your round (such as in a surprise round). The descriptions of specific actions, below, detail which actions allow this option.
4) Free Action: Free actions consume a very small amount of time and effort, and over the span of the round, their impact is so minor that they are considered free. You can perform one or more free
actions while taking another action normally. However, the DM puts reasonable limits on what you can really do for free. For instance, calling out to your friends for help, dropping an object, and
ceasing to concentrate on a spell are all free actions.
Not an Action: Some activities are so minor that they are not even considered free actions. They literally don’t take any time at all to do and are considered an inherent part of doing something else.
For instance, using the Use Magic Device skill (page 85) while trying to activate a device is not an action, it is part of the standard action to activate a magic item.
Restricted Activity: In some situations (such as when you’re slowed or during a surprise round), you may be unable to take a full round’s worth of actions. In such cases, you are restricted to taking
only a single standard action or a single move action (plus free actions as normal). You can’t take a full-round action (though you can start or complete a full-round action by using a standard action;
see below).
Attacks of Opportunity:
The melee combat rules assume that combatants are actively avoiding attacks. A player doesn’t have to declare anything special for her character to be on the defensive. Even if a character’s miniature figure is just standing there on the battle grid, you can be sure that if some orc with a falchion attacks the character, she is weaving, dodging, and even threatening the orc with a weapon to
keep the orc a little worried for his own hide.
Sometimes, however, a combatant in a melee lets her guard down. In this case, combatants near her can take advantage of her lapse in defense to attack her for free. These free attacks are called attacks of opportunity.
Threatened Squares: You threaten all squares into which you can make a melee attack, even when it is not your action. Generally, that means everything in all squares adjacent to your space
(including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you’re unarmed, you don’t normally threaten any squares and thus
can’t make attacks of opportunity.
Reach Weapons: Most creatures of Medium or smaller size have a reach of only 5 feet. This means that they can make melee attacks only against creatures up to 5 feet (1 square) away. However, Small
and Medium creatures wielding reach weapons (such as a longspear) threaten more squares than a typical creature. For instance, a longspear-wielding human threatens all squares 10 feet (2 squares)
away, even diagonally. (This is an exception to the rule that 2 squares of diagonal distance is measured as 15 feet.) In addition, most creatures larger than Medium have a natural reach of 10 feet or
more; see Big and Little Creatures in Combat, page 149.
Provoking an Attack of Opportunity: Two kinds of actions can provoke attacks of opportunity: moving out of a threatened square and performing an action within a threatened square.
Moving: Moving out of a threatened square usually provokes an attack of opportunity from the threatening opponent. There are two common methods of avoiding such an attack—the 5-foot-step (see
page 144) and the withdraw action (see page 143).
Performing a Distracting Act: Some actions, when performed in a threatened square, provoke attacks of opportunity as you divert your attention from the battle. Casting a spell and attacking with a ranged weapon, for example, are distracting actions. Table 8–2: Actions in Combat notes many of the actions that provoke attacks of opportunity. Remember that even actions that normally provoke attacks of opportunity may have exceptions to this rule. For instance, a character with the Improved Unarmed Strike feat doesn’t incur an attack of opportunity for making an unarmed attack.
Making an Attack of Opportunity: An attack of opportunity is a single melee attack, and you can only make one per round. You don’t have to make an attack of opportunity if you don’t want to.
An experienced character gets additional regular melee attacks (by using the full attack action), but at a lower attack bonus. You make your attack of opportunity, however, at your normal attack
bonus—even if you’ve already attacked in the round.
An attack of opportunity “interrupts” the normal flow of actions in the round. If an attack of opportunity is provoked, immediately resolve the attack of opportunity, then continue with the next
character’s turn (or complete the current turn, if the attack of opportunity was provoked in the midst of a character’s turn).
Combat Reflexes and Additional Attacks of Opportunity: If you have the Combat Reflexes feat (page 92), you can add your Dexterity modifier to the number of attacks of opportunity you can make in a round. This feat does not let you make more than one attack for a given opportunity, but if the same opponent provokes two attacks of opportunity from you—such as by moving out of a threatened square and then casting a spell in a threatened square—you could make two separate attacks of opportunity (since each one represents a different opportunity). Moving out of more than one square threatened by the same opponent in the same round doesn’t count as more than one opportunity for that opponent. All these attacks are at your full normal attack bonus.