In this thesis, we firstly introduce almost and pseudo almost periodic func-tions and sequences. Next, we give some basic concepts and sever al well-known facts on difference equations. Later, we prove the existence and uniqueness of the bounded almost and pseudo almost periodic solutions of specific difference sys-tems. Finally, we consider the stability of solutions of these systems and present an example.
 

Keywords:  Almost periodic, pseudo almost periodic, sequence, difference equa-tion, stability.