Spatial optical soliton represents an optical beam propagating in a nonlinear medium without changing its shape. Because of their robustness and potential application in all-optical switching, solitons have been a subject of intense theoretical and experimental studies. In this talk I will present an overview of our research on spatial solitons in photorefractive crystals. In particular, I will discuss soliton formation, stability and interaction. I will also present results of our current investigations of nonlinear beam propagation in periodic structures. These include formation of discrete and gap solitons and their steeering properties.