**data** source: any system providing retrieval mechanisms (usually, an API) to access **data** related to software development: source code management, issue tracking, code review, synchronous or asynchronous communication, testing, collaborative documentation writing, Q/A forums, etc. Examples of a **data** source are a Git server, a Bugzilla instance, a Mailman archive, or some Slack instance. kind of **data** source: all **data** sources with the same retrieval API. Examples of kinds of **data** sources are "Git", "Bugzilla", "Mailman", or "Slack". repository: a part of a **data** source, usually corresponding to the **data** managed for a certain project. Examples of repositories are a Git repository, a Bugzilla issue tracker, a mailing list archive in a Mailman instance, or a Slack channel. index: all **data** corresponding to a certain kind of **data** source, as it is stored in the GrimoireLab database. Indexes may be raw, with **data** as similar as possible to the one provided by the **data** sources, or enriched, which are tailored to easy visualization and reporting.