Dive Into Mark has a great look at Why do we have an IMG element? and traces its origins back to the original proposal, manages to fit in the history of more than a couple of browsers, and ties it all up nicely with a look at the state of the HTTP/HTML/Browser world today.
Some of the operating systems from 1993 still exist, but none of them are relevant to the modern web. Most people today who "experience" the web do so on a PC running Windows 2000 or later, a Mac running Mac OS X, a PC running some flavor of Linux, or a handheld device like an iPhone. In 1993, Windows was at version 3.1 (and competing with OS/2), Macs were running System 7, and Linux was distributed via Usenet. (Want to have some fun? Find a graybeard and whisper "Trumpet Winsock" or "MacPPP.")
As a note, I shudder thinking about Trumpet Winsock..... not sure if those are shudders of reminiscing joy, or repressed fear. Definitely makes me glad things have moved on!
Great stuff Mark!