From Wikipedia:
Constructed Formats:
Block Constructed formats are defined by the cycle of three sets of cards in a given block. For example, the Ravnica block format consists of Ravnica: City of Guilds, Guildpact, and Dissension. Only cards that were printed in one of the sets in the appropriate block can be used in these formats.
Standard contains the current block, the last completed block, and the most recent core set (except in the intervening months between the core set release in summer and rotation in October, wherein the most recent core set and previous core set are both Standard legal). The Standard card pool undergoes a "rotation" each year in October. Currently the Standard card pool consists of the Zendikar block, the Magic 2011 core set, and the Scars of Mirrodin block, currently composed of the Scars of Mirrodin set and the newly released "Mirrodin Besieged" set.
Extended is the format where all Magic blocks and core sets issued during the last four years are legal. As in Standard, the pool rotates once a year in October. The current Extended format consists of Lorwyn, Shadowmoor, Shards of Alara, Zendikar, Scars of Mirrodin, and their corresponding blocks; and the Magic 2010, and Magic 2011 core sets.
Vintage and Legacy are considered "Eternal Constructed" formats because the card pool never rotates. This means that all the sets that are currently legal will continue to be legal and any new sets will automatically be included in the legal card pool. The only banned cards in Vintage are cards using the "ante" mechanic and a few other cards that the DCI considers inappropriate for competitive Magic. Because of the expense in acquiring the scarce old cards to play competitive Vintage, many Vintage tournaments permit players to proxy a certain number of cards.
Limited Formats:
In "Limited" tournaments players construct decks using some measure of sealed booster packs and basic land. The decks in Limited tournaments must be a minimum of forty cards, and all unused cards function as the sideboard. In contrast to "Constructed" tournaments, the player is not restricted to exchange cards on a one-for-one basis when sideboarding, so long as the player adheres to the forty card minimum. The rule that a player may use only four copies of any given card does not apply.
In "Sealed Deck" tournaments, each player receives six booster packs (each containing 15 cards) from which to build his or her deck. They may then add as many basic lands of their choice to their deck, as needed.
In a "Booster Draft", several players (usually eight) are seated around a table and each player is given three booster packs. Each player opens a pack, selects a card from it, and passes the remaining cards to the next player. Each player then selects one of the remaining cards from the pack he or she just received, and passes the remaining cards again. This continues until all of the cards are depleted. Players pass left for the first and third packs, and right for the second. Players then build decks out of any of the cards that they selected during the drafting. Talking, signaling, and showing cards is forbidden during the drafting process.
Battleground runs Standard tournaments and Draft tournaments weekly. If you have any other questions, shoot me an email or PM.
