Windows 3.1 turns 30 this year. While this updated version of Windows 3 was relatively short-lived, it turned out to be some big steps.
According to The Register, Windows 3.1 was released on April 6, 1992 as the successor to Windows 3 and brought some pretty noticeable changes with it. It was shipped on floppy disks and is believed to be the first version of Windows available on CD.
Windows 3.1 introduced the TrueType font system. These are super-readable font styles developed by Apple and released for free to try and become a standard against the efforts of Adobe and others. Microsoft put a lot of effort into these readable fonts that still exist today, such as Times New Roman and Arial.
With their design structure to maintain certain sizes, fonts are versatile and can be scaled, rotated, and even bolded and italicized. They are specifically designed to be read at lower resolutions, and given the screens people were working on at the time, this must have been very easy on the eyes.
Windows 3.1 also marked the beginning of a new Microsoft concept called The Registry. These are hidden settings in Windows that act as a database for Windows and compatible applications that are still in use today.