In May 2016, I attended a week-long workshop on Branching Problems for Reductive Groups at the Institut Mittag-Leffler (Djursholm, Sweden).

I gave a lecture on *An overview of representations of reductive algebraic groups*; essentially everything I discussed can be found in the text of Jens Jantzen on the representation theory of algebraic groups. I tried to focus on things that seem to me to be relevant to the difficulties presented by modular representation theory to “branching problems”:

- (Hochschild) cohomology,
- the description of simple representations for reductive groups,
- reduction mod
*p*and - the Jantzen filtration of Weyl modules
*Δ*(*λ*).

Here are the slides from my talk.