401. Library

401.1. When a game begins, each player’s deck becomes his or her library.

401.2. Each library must be kept in a single face-down pile. Players can’t look at or change the order of cards in a library.

401.3. Any player may count the number of cards remaining in any player’s library at any time.

401.4. If an effect puts two or more cards on the top or bottom of a library at the same time, the owner of those cards may arrange them in any order. That library’s owner doesn’t reveal the order in which the cards go into his or her library.

401.5. If a spell or ability causes a card to be drawn while another spell is being cast, the drawn card is kept face down until that spell becomes cast (see rule 601.2h). While face down, it’s considered to have no characteristics. The same is true with relation to another ability being activated.

401.6. Some effects tell a player to play with the top card of his or her library revealed, or say that a player may look at the top card of his or her library. If the top card of the player’s library changes while a spell is being cast, the new top card won’t be revealed and can’t be looked at until the spell becomes cast (see rule 601.2h). The same is true with relation to an ability being activated.

401.7. If an effect causes a player to play with the top card of his or her library revealed, and that particular card stops being revealed for any length of time before being revealed again, it becomes a new object.

401.8. If an effect causes a player to put a card into a library “Nth from the top,” and that library has fewer than N cards in it, the player puts that card on the bottom of that library.

402. Hand

402.1. The hand is where a player holds cards that have been drawn. Cards can be put into a player’s hand by other effects as well. At the beginning of the game, each player draws a hand of seven cards. (See rule 103, “Starting the Game.”)

402.2. Each player has a maximum hand size, which is normally seven cards. A player may have any number of cards in his or her hand, but as part of his or her cleanup step, the player must discard excess cards down to the maximum hand size.

402.3. A player may arrange his or her hand in any convenient fashion and look at it as much as he or she wishes. A player can’t look at the cards in another player’s hand but may count those cards at any time.

403. Battlefield

403.1. Most of the area between the players represents the battlefield. The battlefield starts out empty. Permanents a player controls are normally kept in front of him or her on the battlefield, though there are some cases (such as an Aura attached to another player’s permanent) when a permanent one player controls is kept closer to a different player.

403.2. A spell or ability affects and checks only the battlefield unless it specifically mentions a player or another zone.

403.3. Permanents exist only on the battlefield. Every object on the battlefield is a permanent. See rule 110, “Permanents.”

403.4. Whenever a permanent enters the battlefield, it becomes a new object and has no relationship to any previous permanent represented by the same card, except for the cases listed in rule 400.7. (This is also true for any objects entering any zone.)

403.5. Previously, the battlefield was called the “in-play zone.” Cards that were printed with text that contains the phrases “in play,” “from play,” “into play,” or the like are referring to the battlefield. Cards that were printed with that text have received errata in the Oracle card reference.