Each family subdirectory contains the `.ttf` font files served by Google Fonts, plus a `METADATA.pb` file with metadata for the family, and a `DESCRIPTION.en_us.html` with a description of the family in US English.
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).
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 a [learning game that takes just 15 minutes](https://try.github.io).
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.
Source files for each family are often available from the designer, or from https://github.com/googlefonts
These fonts are usually the result of collaborative projects, where you are invited to discuss issues with the designers and even contribute to their on-going development.