With topics, you can explore repositories in a particular subject area, find projects to contribute to, and discover new solutions to a specific problem.
Repository admins can add any topics they'd like to a repository's main page. Helpful topics to classify a repository include the repository's intended purpose, subject area, community, or language.
Additionally, GitHub uses machine learning to analyze public repository content and generate suggested topics that repository admins can accept or reject. Private repository content is not analyzed and does not receive topic suggestions.
Public and private repositories can have topics, although you will only see private repositories that you have access to in topic search results.
You can search for repositories that are associated with a particular topic. For more information, see "Searching repositories."