The different types of audio file formats refer to the digital storing of audio on either a personal computer or media playing device. There have been, and remain today, a number of different ways to store digitised audio, many of which are optimised for varying purposes. Audio file formats are generally split into two separate types: compressed and raw.
Audio file compression is a method of decreasing the size of an audio file, as raw formats can be very large. Although this is not as big a 
concern today due to the increase in storage space across practically every device.
One of the most common file formats that is still in regular use today is the the MP3 file. MP3s, and other compressed audio files, take advantage of limitations in human hearing. It was first theorised in 1894 that a tone could be rendered inaudible by a tone of a lower frequency, this idea was further expanded on during the 1950s by Richard Ehmer, who compiled a set of auditory curves regarding the phenomenon first theorised by Alfred Mayer. This information was first use to create a psychoacoustic masking codec in 1979.