LOL is a text file that contains source code written in LOLCODE programming language. LOLCODE is a not a proper programming language but more of a humorous atempt at code writting process. LOL files are inspired by meme images that depict cats (‘lolcats’).

LOL file extension is not used for any proper application developed by programmers. LOLCODE is a rather limited language and is considered a mere curio. However, LOLCODE is popular among hackers and therefore users should maintain caution when having to deal with LOL files.