MUGs may be community groups, government agencies, corporations, schools, universities, online, professional organizations, or software specific.
The following is a 2005 list[1] from the Apple User Group Locator of 19 still active MUGs that had initial meeting dates in 1975 - 1978 (note that these MUGs supported Apple products prior to the Macintosh computer line with original meeting dates that predate the Macintosh computer line): MUGs exploded in size in the 1980s and were a primary method of distribution of freeware and shareware software.
Computer hardware and software companies found MUGs to be a valuable place to provide information about their products.
While many of these companies still speak at MUGs, the Internet has replaced many of the tools of information and software access that were not as available to the public prior to the late 1990s.
Today's MUGs are generally smaller, but have had some revitalization with the increased popularity of Apple Inc. products in the mid-2000s.