Originally Posted by: allyguitarHi can anyone teach me what is modulation in a simple way? Whats the differnece between transpose and modulation?

Transposition is a complete change of key signature. Modulation is a using notes or chords from a different key, but still remaining in the original key signature (in other words, without changing completely to that other key signature).

To contrast, a modulation can be thought of as a "temporary" change of key signature. :)

Playing a melody or chord progression in the key of A major, then changing it to the key of E major is a transposition.

Playing a melody or chord progression in the key of A major, then playing a B major chord in the middle of it, but still remaining overall in the key of A major is a modulation.

http://en.wikipedia.org/wiki/Transposition_(music)
http://en.wikipedia.org/wiki/Modulation_(music)