changelog

A changelog is a record of notable changes made to a project over time. It documents new features, bug fixes, improvements, deprecations, removals, and other significant alterations across versions. The primary purpose is to inform users, developers, and integrators about what changed, why it changed, and how the changes may affect compatibility or usage.

Changelogs are typically maintained as a dedicated file in the project repository, often named CHANGELOG.md, and are released alongside software versions. Entries are usually organized by version number and date, and may be grouped into categories such as Added, Changed, Deprecated, Removed, Fixed, and Security. Many projects follow the Keep a Changelog standard to promote a consistent, human-readable format, while others use automated approaches that generate entries from commit messages.

Changelog practice is closely linked to versioning strategies such as semantic versioning, where MAJOR, MINOR, and PATCH releases reflect the nature of changes and compatibility implications. A well-maintained changelog helps users assess impact, plan upgrades, and audit changes for security or compliance, and can aid support and documentation efforts.

Historically, changelogs emerged from the need to track software evolution and to communicate changes to stakeholders. With distributed development and open source collaboration, formal changelogs have become a common expectation for many projects and platforms.