Three kayas

Dharmakaya is the Absolute. It is the source of everything including Buddha activity, and is not different from the Void. It is not usually experienced except by fully realized beings. It is not normally "prayed to," though it is saluted or praised.  Its nature is the subject of discussion.  The samboghakaya is rarely experienced.  Its manifestation is as described in the images used in visualization, and in stories told of deities. It is Manifestation that permits description, and has been referred to as "timeless communication."  The sound Ah, the expression of joyous wonder, is written and used to evoke it.   The nirmanakaya is the third "body."  It is the phenomenal world; our reality.  The sound Hum, which actually means us in Sanskrit (in Tibetan it is rendered as Hung).  It is the here-and-now, with all its future potential. It may be helpful to think of the three as: abstract, mythic and human realms.