Advaita is a Sanskrit word that literally means “not two”. Synonyms of Advaita are non-duality (nonduality, non duality). Advaita is not a philosophy or a religion. Non-duality is an experience in which there is no separation between subject and object; a “me” and the rest of the universe; a “me” and God. It is the experience of consciousness, our true nature, which reveals itself as absolute happiness, love and beauty. Consciousness is defined as that, whatever that is, which is aware of these very words right here, right now.
Article on nonduality.