Samadhi, is the ultimate goal of yoga, union with the divine infinite bliss that is God. Arrival at this state can come from deep and constant dhyana (meditation). This is a state of consciousness described by many names. I highly recommend further reading on the topic, but don’t get lost. Great gurus say this is a state that can only be known through experience, rather than intellectual grappling, therefore a steady yoga practice is recommended to know samadhi.