Informal Friday Seminar: Cliff -- An introduction to sheaves on stacks

We will review/learn the definition of a stack, and practice with examples, including
quotient stacks.  Then we will discuss how to define sheaves on stacks (both ordinary
and dg versions), and will unwind the definitions in our quotient stack examples to
recover the notion of equivariant sheaves on varieties with G-action.  (For example,
when the variety is a point with the trivial G-action, these are just representations of
G.)