The ABC file extension is primarily associated with the ABC music notation language, which is a shorthand form of musical notation using the ASCII character set. It was originally designed by Chris Walshaw in the early 1990s to facilitate the sharing of traditional folk music over the internet and via email. Unlike complex binary formats or XML-based music files, ABC files are plain text, making them extremely lightweight and easy to read or edit with any basic text editor. The format allows musicians to represent melodies, rhythms, and metadata like titles, composers, and key signatures using simple letters, numbers, and symbols. Over time, the format has evolved to support multi-voice compositions, complex arrangements, and detailed ornamentation. It is widely used in the folk and traditional music communities and is supported by a variety of specialized software tools that can render the text into high-quality sheet music in PDF or PostScript formats, or play it back as MIDI audio. Because of its simplicity and open-source nature, it remains a popular choice for archiving large collections of tunes and for use in web-based music applications. Its text-based nature also makes it highly compatible with version control systems, allowing musicians to track changes to their compositions over time.