abstract: In unpublished notes from 1960, Richard Thompson defined the three groups F < T < V, which act respectively on the interval, circle and Cantor set. Their definition might appear very specific, but these groups have an incredibly rich theory, bizarre combinations of properties, intricate dynamics, and many mysteries surrounding them. I will focus on F, and the long-standing open question of whether it is amenable or not. My hope is that by the end of this minicourse, you will have a new group in your personal library of favourite groups, and a better appreciation of just how strange some groups can be.