In Buddhism, a Bodhisattva (from the Sanskrit words bodhi, meaning "awakened", and sattva, meaning "existence" or "living being") is an enlightened person who delays reaching Nirvana in order to help others reach Nirvana.
Mahayana and Theravada Buddhism have different attitudes towards Bodhisattvas. In the Theravada tradition, an Arhat has achieved complete enlightenment (personal liberation) as an individual without becoming a Bodhisattva or a Buddha. In contrast, the Mahayana look on such an Arhat or Pratayeka's realization of "individual liberation" as somewhat selfish. In the Mahayana one must become a Bodhisattva in order to realize Anuttara Samyak Sambodhi or the full and complete enlightenment of a Buddha with the wish of Bodhichitta. Bodhichitta is the great vow and attitude to wish to realize Buddhahood in order to liberate all sentient beings.
The Bodhisattva Vow is recited three times daily throughout the Mahayana Buddhist world:
However innumerable sentient beings are, I vow to save them.
However inexhaustible the defilements are, I vow to extinguish them.
However immeasurable the dharmas are, I vow to master them.
However incomparable enlightenment is, I vow to attain it.