Definition: It's a file used to update a system log. The term "CHANGELOG" refers to updates, usually related to bugs or feature enhancements in software systems, typically published after each major release. The word "TXT" stands for text/plain (text data) and thus acts as the delimiter to separate files within a specific version of a program. For example, if you're using a Linux-based operating system, "CHANGELOG.TXT" is used for system logs that describe changes made during development.