Last time, we saw that the lattice of torsion classes is completely semidistributive. Motivated in part by this fact, Reading–Speyer–Thomas proved a fundamental theorem of finite semidistributive lattices. We'll give the necessary definitions to state the theorem, give some examples, and explain the connection to torsion classes. Time permitting, we will also describe canonical join representations and the canonical join complex of a finite semidistributive lattice.