Windows 3.11
{Infobox OS version | name = Windows 3.1x | family = Microsoft Windows
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| | caption = Screenshot of Windows XP Service Pack 3 | developer = Microsoft | website = Windows XP: Homepage | first_release_date = Template:Start date | first_release_url = http://www.microsoft.com/presspass/press/2001/aug01/08-24WinXPRTMPR.mspx | release_version = 5.1.2600.5512 Service Pack 3 (x86 SP3) | release_date = Template:Release date | release_url = http://forums.microsoft.com/TechNet/ShowPost.aspx?PostID=3214173&SiteID=17 | source_model = Closed source, Shared source | license = MS-EULA | supported_platforms = x86, x86-64, IA-64 | kernel_type = Hybrid kernel | support_status = Mainstream support (only with Service Pack 2 and 3) | }}
Windows 3.1x puhul on tegemist 16-bitiste operatsioonisüsteemide seeriaga, mida Microsoft tootis personaalarvutitele . Tooteseeria algas versiooniga Windows 3.1, mis tuli müügile 1992 aasta märtsis kui Windows 3.0 järglane. Järgmised tooted, mis kuulusid seeriasse, lasti välja ajavahemikul 1992-1994, kuni need asendati Windows 95-ga. 2001. aastal lõpetas Microsoft Windows 3.1x-le toe pakkumisega.
