The file formats that work best for transcription services are audio formats. These formats may include uncompressed audio, such as WAV, that are made from sound waves and involve no processing. Lossy file formats, such as MP3, are popular with transcription services, as they feature smaller file sizes and are easier to transfer. Lossless file formats, such as WMA, enable the file to be reduced in size without the loss of quality. These three types of file formats are the most popular among transcription services.