Microsoft added some peer-to-peer workgroup abilities and domain networking support to Windows 3.1 in 1992 and labeled the upgrade Windows for Workgroups. This would be the first time that Microsoft Windows was natively network-aware. The upgrade replaced Windows 3.1 at both the retail and OEM levels and was also available for free through Microsoft's FTP site.

Windows for Workgroups was used in local area networks (LANs) and on stand-alone PCs and laptop computers of the day. The major interest in the upgrade belonged to corporate users, however, as the increased security, file and printer sharing, centralized configuration improved support for Novell NetWare networks, and remote access services (RAS). Windows for Workgroups also introduced Microsoft's new 32-bit file system, allowing 32-bit applications to run on computers equipped with the upgrade. New programs included in the package included Microsoft Mail and Schedule+ (a workgroup scheduler).

Ultimately at this stage in computer evolution many consumers had no need for these networking features, leading to massive amounts of the software sitting in storage complexes, earning the upgrade the nickname "Windows for Warehouses". Windows for Workgroups was replaced with Windows 95.


References:
http://www.microsoft.com/windows/WinHistoryDesktop.mspx
http://members.fortunecity.com/pcmuseum/windows.htm
http://www.pcmag.com/article2/0,4149,64379,00.asp