April 6, 1992: This updated version of Windows established some features that are taken for granted today. This includes the CTRL-ALT-DEL command to avoid rebooting your computer, and allowing you to cut and paste from one application to another.
As internet access moved forward, Windows 3.1 also supported modem speeds up to 9600 bps.
To explore more about early features in Windows, there are several books in the catalog:
Windows 3.1 Secrets, by Brian Livingston, QA76.76 .W56 L582 1992
The Complete Idiot’s Guide to Windows, by Paul McFedries, QA76.76 .W56 M5183 1994
Source: Computer History.