A text file traditionally included in the top-level directory of a software distribution, containing pointers to documentation, credits, revision history, notes, etc. Originally found in Unix source distributions, the convention has spread to many other products. The file may be named README, READ.ME, ReadMe or readme.txt or some other variant.
In the Macintosh and IBM PC worlds, software is not usually distributed in source form, and the README is more likely to contain user-oriented material like last-minute documentation changes, error workarounds, and restrictions.
The README convention probably follows the famous scene in Lewis Carroll's "Alice's Adventures In Wonderland" in which Alice confronts magic munchies labeled "Eat Me" and "Drink Me".