The word ‘Namaste’, in Sanskrit, contains two words: ‘Namah’ and ‘te’. ‘te’ - means ‘to you’. ‘Namah’ - means ’salutations’. It usually implies, I bow down to the God within you. The same is done when one addresses God directly. Primarily, it is done to erase our ego. Invariably, our psychology is that others should recognize me as great & they should respect me. That is, we have the superiority complex. By doing namaskar, we shall be effacing our ego and become humble, which is a primary condition for Spiritual Progress.
The act if greeting by joining palms together is called namaskar.