In Magic: The Gathering (MTG), a spell is any type of card cast by a player. Here are some key points to keep in mind:

• A spell is a card on the stack. When you cast a card, it becomes a spell until it resolves.
• Cards in your hand arent spells, and permanents on the battlefield dont count as spells.
• Creatures are spells when you cast them, and while they remain on the stack. Once they resolve and enter the battlefield, they become permanents instead of spells.
• Instants and sorceries are spells while theyre on the stack, but nowhere else.
• Activated abilities use the stack, but they are not spells.

In summary, a spell in MTG is any non-land card that is cast by a player and placed on the stack until it resolves, and it includes creatures, instants, and sorceries. Cards in your hand and permanents on the battlefield are not spells, and activated abilities are not spells either.