  These are lecture notes based on a series of lectures presented at the XIII
Modave Summer School in Mathematical physics aimed at PhD students and young
postdocs. The goal is to give an introduction to some of the recent
developments in understanding holography in two bulk dimensions, and its
connection to microscopics of near extremal black holes. The first part reviews
the motivation to study, and the problems (and their interpretations) with
holography for AdS$_2$ spaces. The second part is about the Jackiw-Teitelboim
theory and nearly-AdS$_2$ spaces. The third part introduces the
Sachdev-Ye-Kitaev model, reviews some of the basic calculations and discusses
what features make the model exciting.
