This is an introductory textbook on statistical mechanics. It is suitable for an undergraduate physics major studying the subject for the first time. The only required prerequisites are multivariable calculus and classical mechanics. You can read it online at https://peastman.github.io/statmech/.
It is written in Sphinx format. To build it as HTML, type
make html
To build it as a PDF, type
make latexpdf
The generated content will be in build/html or build/latex, respectively.