Magic: The Gathering is a trading card game, the first of its kind, created by Richard Garfield and introduced in 1993 by Wizards of the Coast. Magic continues to thrive, with approximately twelve million players as of 2011. Magic can be played by two or more players each using a deck of printed cards or a deck of virtual cards through the Internet-based Magic: The Gathering Online or third-party programs.Each game represents a battle between mighty wizards, known as "planeswalkers", who employ spells, artifacts, and creatures depicted on individual Magic cards to defeat their opponents. Although the original concept of the game drew heavily from the motifs of traditional fantasy role-playing games such as Dungeons & Dragons, the gameplay of Magic bears little similarity to pencil-and-paper adventure games, while having substantially more cards and more complex rules than many other card games. (Wikipedia)
To play, you first draw seven cards. [This is just how I learned it] You play the mana (land) you have. You can only play one mana per turn. But you have the mana for the entire round unless certain cards say otherwise. You 'tap' the mana by turning it to the side to play a card, which uses mana. Say a card has 3 grey(any type) and 2 mountain. You play that card and tap the mana until your next turn, where you can un-tap it and tap it again. It's a very fun game, and has even
caused Florida Man to kill other Florida Man.