# GitBook FAQ

#### Should I use an `.html` or `.md` extensions in my links?

You should always use `.md` extensions for your relative links, GitBook will automatically replace these links by the right value when the pointing file is referenced in the Table of Contents.

#### Can I create a GitBook in a sub-directory of my repository?

Yes, GitBooks can be created in sub-directories. GitBook.com and the CLI also looks by default in a series of [folders](structure.md).