A changelog is a log or record of changes made to a project, such as a website

Website

A website, also written as Web site, web site, or simply site, is a collection of related web pages containing images, videos or other digital assets. A website is hosted on at least one web server, accessible via a network such as the Internet or a private local area network through an Internet...

 or software project, usually including such records as bug fixes, new features, etc. Most open source

Open source

The term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...

 projects include a changelog as one of the top level files in their distribution.

Although the canonical naming convention for the file is ChangeLog, it is sometimes alternatively named as CHANGES or HISTORY (NEWS is usually a different file reflecting changes between releases, not between the commits). Some project maintainers will append a .txt suffix to the file name.

Some revision control

Revision control

Revision control, also known as version control and source control , is the management of changes to documents, programs, and other information stored as computer files. It is most commonly used in software development, where a team of people may change the same files...

 systems are able to generate the relevant information that is suited as a changelog.

Format

Changelog files are organized by paragraphs, which define a unique change within a function or file.
Most changelog files follow the following format:

YYYY-MM-DD  John Doe  



    * myfile.ext (myfunction): my changes made

    additional changes



    * myfile.ext (unrelated_change): my changes made

    to myfile.ext but completely unrelated to the above



    * anotherfile.ext (somefunction): more changes

Note that between the date and the name, and again between the name and the email address, there are two spaces each. It is common to enclose the email address in < and >. The Emacs Editor

Emacs

Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...

 creates such entries when creating additional changelog entries.

Changelogs in Wikis

Most Wiki

Wiki

A wiki is a website that allows the creation and editing of any number of interlinked web pages via a web browser using a simplified markup language or a WYSIWYG text editor. Wikis are typically powered by wiki software and are often used collaboratively by multiple users. Examples include...

 software includes changelogs as a fundamental feature (often called history in this context). For example, the "View History" link at the top of a Wikipedia

Wikipedia

Wikipedia is a free, web-based, collaborative, multilingual encyclopedia project supported by the non-profit Wikimedia Foundation. Its 20 million articles have been written collaboratively by volunteers around the world. Almost all of its articles can be edited by anyone with access to the site,...

entry links to that page's changelog. This feature is vital for complying with the attribution requirements of some copyright licenses.

External links

• Explanations, how to write Changelog entries in open source projects
• The Changelog, a podcast and blog that covers what's fresh and new in Open Source (essentially covering "the changelog" of open source projects)
• PAD, one of the many changelog techs.