The Lunar Environment is a harsh environment with extreme temperature differences. In the dark, the Moon's surface temperature falls to 70 Kelvins, while in the sun, the surface heats up to 230 Kelvins. Trace amounts of water vapor have been found, possibly from the water ice undergoing sublimation. Besides small amounts of various gases, the atmosphere of the moon is almost a vacuum; its entire atmosphere weighs approx. less than 10 metric tons.
The soil of the Moon is sand - like; much of this "sand" is comprised of silicon dioxide. This compound is highly compacted on the Moon. After this layer of sediment, layers of bedrock can be found for several kilometers.
A unique property of the Moon is that there is a pattern of 2 weeks of sunlight followed by 2 weeks of nighttime. It is imperative that a rover sent to the Moon must cope with this strange pattern.
NASA's early exploration of the Moon began with the Mariner and the Ranger probes. While the Mariners were only observers (i.e. space probes that orbited around the Moon while sending back snapshots of the surface), the Rangers were sent to crash into the Lunar surface while taking the first close-up pictures of the surface. After the famed Apollo Missions of the late 1960's to early 1970's, there has been no new missions to the Moon.
Fun fact: In the Apollo 14 mission, astronaut Alan Sheppard brought golf clubs with him to play a round of Moon golf. He later was reprimanded for golfing, as the ball may have damaged spacecrafts.
On a closing note, one of the most commonly - known facts of the Moon is that its gravity is 1/6 of that of Earth's. This means that a lunar rover that weighs 100 lbs. on Earth is only 16 2/3 lbs. on the Moon. This is an important fact because a rover can carry more weight with the same motors.