What is a changelog?
A changelog is a file which contains a curated, chronologically ordered list of notable changes for each version of a project.
Why keep a changelog?
To make it easier for users and contributors to see precisely what notable changes have been made between each release (or version) of the project.
Who needs a changelog?
People do. Whether consumers or developers, the end users of software are human beings who care about what's in the software. When the software changes, people want to know why and how.