  In these notes I review the basic concepts of the effects of interactions on
quantum particles. I focuss here mostly on the case of fermions, but several
aspects of interacting bosons are mentioned as well. These notes have been
voluntarily kept at an elementary level and should be suitable for students
wanting to enter this field. I review the concept of Fermi liquid, and then
move to a description of the interaction effects, as well as the main models
that are used to tackle these questions. Finally I study the case of one
dimensional interacting particles that constitutes a fascinating special case.
