What is the spirit in tempest?

In "The Tempest", the spirit is Ariel. Ariel is a powerful spirit of the air who serves the sorcerer Prospero. He is invisible and can take on any shape. He is Prospero's loyal and obedient servant and helps him to enact his revenge on his enemies. Ariel is also a mischievous and playful spirit who enjoys tormenting Prospero's enemies.