Enchantments are permanents. You cast one during a main phase while the stack is empty, and when it resolves it enters the battlefield and stays there. Unlike an instant or sorcery, it does not resolve and go to the graveyard; it keeps applying its abilities as long as it remains on the battlefield. Many enchantments are Auras that attach to a permanent or player, while others simply sit in play and affect the game globally.
In decks, enchantments fill support and control roles: they can boost your creatures, weaken or lock down opposing permanents, tax actions, or generate recurring value each turn. Because they can be difficult for some colors to interact with, enchantment-heavy strategies often aim to build an advantage that compounds over several turns.
