Vamana

Vamana is one of the avatars or incarnations of Lord Vishnu. He is one of the 10 major incarnations (Dashavatar) of Lord Vishnu. Vamana is the fifth of the ten dashavatars.￼

Mahabali's Yajna
Mahabali was a very powerful asura who conquered all the worlds. But he was a devotee of Vishnu. He was the son of Virochana; the grandson of Prahlada and the great grandson of Hiranyakashipu, who was slain by Narasimha. He was a noble and pious asura but he was intent on conquering the world. After conquering Amaravati, the abode of Indra, the king of gods, he decided to give away gifts in honour of his victory. But he didn't invite the devas, as they would ask their lands back. So the devas turned to Vishnu, the restorer of balance in the world. Vishnu, at first didn't respond, as Mahabali was his devotee, but later he accepted. So, he took birth as a young dwarf in the house of Kashyapa and Aditi.

Shukrachaya's Denial
As Vamana entered the yajna, Sukracharya, the teacher of the asuras, noticed him and tries to warn Mahabali. Mahabali doesn't listen to him as he has to fulfill his duties as a king. So, Shukracharya assumes the form of a fly and flies to the entrace of the kamandalu, making sure that water doesn't spill out. In ancient India, if a king is offering something to someone, they first sprinkle some water as ritual. As Mahabali, proceeds to sprinkle some water, the water doesn't come out. Vamana takes some grass from nearby, and pokes the entrance, blinding Shukracharya in one eye.

Vamana's Request
After sprinkling some water, Mahabali asks Vamana what he would like. Vamana replies by telling that he wants only 3 steps of land. Mahabali looks puzzled and asks him to confirm. Vamana stands firm on his decision as Mahabali agrees. Then, Vamana grows larger and larger in size until his head would reach the sky. With one foot, he takes all of earth, with another, he takes up the heaven. Vamana asks Mahabali where to place his third step. Mahabali asks to place his third foot on his head. Vamana, touched by the demon king's humbleness, agrees and sends him to Patala, where he can live happily. Thus, the heavens was restored to Indra.

Etymology
Vamana means 'short or small in stature'. It also means 'dwarf bull'.