LIT is a file format used for storing ebook data. LIT documents include DRM information. LIT files are generated using Microsoft ClearType technology that improves image quality on LCD screen displays.

LIT extension is used by default by Microsoft Reader application. LIT format conforms to OeB (Open eBook) specification for ebooks. LIT format lost some of its popularity, but such files may be converted into other formats and viewed on most mainstream ebook readers.