The So'ham mantra has been used for thousands of years to identify oneself with the Universal Reality. In Tantra and Kriya yoga, it is known as ajapa japa - a constant awareness of the mantra, without chanting it. It is also believed that So'hum is an answer to Koham, meaning "Who am I?" The universe answers this question with So'hum, communicating that "You are the same as I am."
As a combination of Sah and Aham, So'hum also symbolizes the power of Shiva and Shakti, forming the male and female powers of the universe.