A land is a permanent card type. You can play one land per turn during your main phase while the stack is empty. Playing a land doesn't use the stack, so opponents can't respond to it. After it enters the battlefield, it stays there unless an effect moves, destroys, or exiles it. Most lands have a basic land type or an ability that lets them tap for mana.
Lands form the mana base of a deck. They provide the resources to cast spells and activate abilities. Some lands trade flexibility for utility, entering tapped or producing multiple colors. Because they're not spells, they don't resolve; they simply enter. Deck builders balance land count, colors, and effects to support the rest of the deck.
