XM most commonly refers to XM Satellite Radio

XM, standing for "extended module", is an audio file type introduced by Triton's FastTracker 2. XM introduced multisampling-capable instruments with volume and panning envelopes, and basic pattern compression. It also expanded the available effect commands and channels, added 16-bit sample support, and offered an alternative frequency table for portamentos.

XM Satellite Radio (XM) was one of the three satellite radio (SDARS) services in the United States and Canada, operated by Sirius XM Holdings. It provides pay-for-service radio, analogous to cable television. Its service included 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional traffic and weather channels and 23 play-by-play sports channels. XM channels were identified by Arbitron with the label "XM" (e.g., "XM32" for "The Bridge").