Abstract: The linear QCD evolution equations for deep inelastic scattering viz. DGLAP and BFKL equations, only involve parton emission processes, and thus are only suitable for dilute parton configurations i.e. for values of Q^2 > 2 GeV^2. In regions where the parton density becomes large, parton absorption processes become important, this  occurs at very high energy (low x) and/or low Q^2 ( < 2 GeV^2). This is known as the saturation region. I will review some models dealing with saturation effects.  The Balitsky-Kovchegov non-linear evolution equation describes DIS processes in the saturation region. I will discuss our numerical solution to an "approximate" BK equation and determine the F_2(x,Q^2) structure function of the proton for all  values of Q^2 and for x < 10^-2, and will indicate how methods based on high parton density and saturation, successfully bridge the "hard" (large Q^2) and the "soft" (non perturbative) regions.