This second course in functional analysis will explore various phenomena in Banach spaces and operator theory around the themes of groups, geometry, measure, and combinatorics. Topics to be covered include unitary representations of groups, amenability, property (T), expanders, Rosenthal's l₁ theorem, the Sauer-Shelah lemma, the Elton-Pajor theorem, entropy, the Johnson-Lindenstrauss lemma, concentration of measure, and Dvoretzky's theorem.