As far as I know, MIDI is the abbreviation of English music instrument digital interface, which is translated into Chinese as "digital musical instrument interface", occupying the smallest space. For example, the ringtones in mobile phones are mostly MIDI. I have made a website, and the background music of the website requires MIDI, and MP3 format is not allowed. Everyone is familiar with MP3 format. It is the audio layer III of the English moving picture expert group, which is translated into Chinese as "the standard audio layer 3 compressed by the moving picture expert". This is a popular digital audio coding and lossy compression format. For example, most music websites and Baidu Music now provide MP3 downloads with good compatibility. RM format is a great contribution of Real Company to the multimedia world, and it is also a contribution to the promotion of online film and television, mainly in video format, which is not as clear as RMVB. WAV format is a sound file format developed by Microsoft, also known as waveform sound file, and it is the earliest digital audio format. It is widely supported by Windows platform and its application, and its sound quality is better than that of CD, but its disadvantage is that it takes up too much file space. To sum up, MIDI is the most suitable background music for websites.