  These lecture notes provide a short review of the status of time dependent
backgrounds in String theory, and in particular those that contain space-like
singularities. Despite considerable efforts, we do not have yet a full and
compelling picture of such backgrounds. We review some of the various attempts
to understand these singularities via generalizations of the BKL dynamics,
using worldsheet methods and using non-perturbative tools such as the AdS/CFT
correspondence and M(atrix) theory. These lecture notes are based on talks
given at Cargese 06 and the dead-sea conference 06.
