There are many different kinds of prayer. Yet all prayer has one basic purpose. We pray not to get something, but to open up a two-way street between us and God so that we (and others) may inwardly become something beautiful that we share with others.
All final spiritual reference is to be the silence beyond sound. The word made flesh is the first sound. Beyond that sound is the transcendent unknown, the unknowable. It can be spoken of as the great silence, or as the void, or as the transcendent absolute.