Lecture notes from Pavel Etingof's class on infinite-dimensional Lie algebras in Spring 2012.

Significant parts of the content are missing, since it was my first encounter with the topic and I was unable to keep up with the pace of the class. Lots of material is messier than it should be.

See also https://darijgrinberg.gitlab.io/algebra/etingof-lie.pdf for a compiled version.