  This manuscript has been prepared as a thesis to obtain the French
"Habilitation \`a diriger des recherches (HDR)" which allows one to supervise
PhD students. I review here my work on the glass and jamming transition. I
tried to explain this subject in a concise and self-contained way, highlighting
what I consider the main motivations for its study and trying to put my work in
a broader perspective. Basically I tried to tell this story in the same way as
I would tell it to a student who contacted me to start a PhD thesis on these
topics.
