Low-x physics is reviewed, with particular emphasis on searches for deviati
ons from Gribov-Lipatov-Altarelli-Parisi (GLAP) evolution of the parton den
sities. Although there are several intriguing indications, both in HERA and
in Tevatron data, as yet there is no unambiguous evidence for other than s
tandard next-to-leading-order GLAP evolution. The framework of dipole model
s and saturation of parton densities is examined and confronted with the da
ta. Although such models give a good qualitative description of the data, s
o do other, more conventional, explanations.