Each family subdirectory contains the `.ttf` font files served by Google Fonts, plus a `METADATA.pb` file with metadata for the family (such as information on the project designer(s), genre category, and license - [learn more](https://github.com/googlefonts/gf-docs/tree/master/METADATA)) and a `DESCRIPTION.en_us.html` with a description of the family in US English.
The `/catalog` subdirectory contains additional metadata, such as profile texts and portrait/avatar images of font designers, and this is open for contributions and corrections from anyone via Github.
If you find a problem with a font file or have a request for future development of a font project, please [create a new issue in this project's issue tracker](https://github.com/google/fonts/issues).
You can also sync the collection with git so that you can update by only fetching what has changed. To learn how to use git, Github provides [illustrated guides](https://guides.github.com) and a [youtube channel](https://www.youtube.com/user/GitHubGuides), and an [interactive learning lab](https://lab.github.com).
Free, open source git applications are available for [Windows](https://git-scm.com/download/gui/windows) and [Mac OS X](https://git-scm.com/download/gui/mac).
The SIL Open Font License has an option for copyright holders to include a Reserved Font Name requirement, and this option is used with some of the fonts.
These fonts are usually the result of collaborative projects, where you are invited to discuss issues with the designers and even contribute to their ongoing development.