Errata

Errata are official changes to card texts, often to clarify card effects or to preserve the effects of cards as the rules of the game change. The official texts of all Magic cards are stored in a document maintained by Wizards of the Coast called the Oracle. In the early days of Magic it wasn't unusual for cards to get huge gameplay-changing errata.

There are two official ways to get the Oracle wordings, from the Oracle Card Reference or from Gatherer.