README

In software distribution and software development, a README file contains information about the other files in a directory or archive of computer software. A form of documentation, it is usually a simple plain text file called README, Read Me, READ.ME, README.txt, or README.md (to indicate the use of Markdown)

The file's name is generally written in uppercase. On Unix-like systems in particular, this causes it to stand out – both because lowercase filenames are more common, and because the ls command commonly sorts and displays files in ASCII-code order, in which uppercase filenames will appear first.