Enchant is the keyword ability that makes a card an Aura and defines what it can attach to. When you cast a card with enchant creature, you choose a creature as its target. If that target is legal when the spell resolves, the Aura enters attached to it; if the target is gone, the spell doesn't resolve. The Aura stays attached and its effect applies. If the enchanted permanent leaves the battlefield, the Aura is put into its owner's graveyard. Enchant can also name lands, modified creatures, or zones.
Enchant cards matter because they keep affecting the same permanent turn after turn, often for less mana than a one-shot effect. But they're fragile: remove the enchanted permanent and the Aura goes with it, often giving your opponent card advantage. Playing with and against enchant cards is about timing, protection, and knowing when the risk is worth it.
