Standard is a rotating group of Magic: The Gathering sets. Most sets enter Standard when they're released and drop out about twenty-one months later. At any given time, Standard will contain between five and eight sets inclusive.
A Standard card is a card printed or reprinted into a set currently in Standard.
A Standard deck contains only Standard cards (60+ of them), may have a sideboard of up to 15 more Standard cards, and apart from basic lands does not have more than four copies of any one card .
Brawl is partially based on Standard—all rotations listed here apply to Brawl—but Brawl has a separate banlist.
Masters sets never enter Standard.