Totally wild to think it’s been around that long.
Here are some other software applications from that era. Note that Emacs is the most venerable.
Microsoft Excel (1985)
PowerPoint (1987)
Adobe Photoshop (1988)
Adobe Illustrator (1985)
Emacs (1976)
LaTeX (1985)
GNU Compiler Collection (GCC) (1987)
…and I bet every toolbar from all 40 years is still there, somewhere, hiding under the fancy new window chrome. 
40 years ago you say? I was a GeoWrite kid…
I’ve come to dislike MS Word, but I have to give credit where it is due. Microsoft Word turned me into a writer. I may be rehashing a story that I’ve recounted here before, I can’t recall.
When I started college in 1992, I had to take the basic college freshman writing courses. I didn’t think I could write—and generally proved myself correct. Microsoft Word for Windows 2.0 came out, and I was ecstatic for it. I was coming from WP 5.1 and was dying for a proper Windows word processor.
I bought Word and loved using it. (As a broke college student, you would not be surprised to learn that I bounced the check to Software Etc. that I used to buy the program and got a call from my bank to bring them the money + an exorbitant NSF fee post haste.)
I spent so much time using it. That i started finding more and more excuses to write. I used the equation editor for writing papers and lab notebook write ups for science classes. I re-typed my notes in Word. I wrote tons and tons of papers. Somewhere along the line, I developed an affinity for writing.
I developed this affinity for writing all because I liked using a tool. The tool didn’t make me a good writer, but spending loads of time writing with it did.
So, let me lift my own glass to Word. Whatever its shortcomings, it has profoundly contributed to where I am today. Thank you, Word. Happy 40th!
And for the midlife crisis: a motorcycle and reconnecting with the college flame embedded generative “AI” and upending our fundamental relationship with writing!
Probably. How does the saying go “90% of people use 10% of the features”? But they don’t use the same 10%.
Maintaining backward compatibility is very important for many large companies and businesses depend on that. That’s one reason Microsoft became the operating system of business. And the same was true of IBM and Avaya for decades, and may still be the case.
First released for the Apple Macintosh. For PC: two years later.
I looked up Avaya on their website and it’s all impenetrable corporate speak. Never heard of them, especially in relation to IBM. What does the company do? Something about communications??
Yes, Telephone/call center systems, etc… AT&T spun off Lucent around 1997, then Lucent spun off Avaya in late 2000. The last system I worked on had an Avaya sticker covering a Lucent sticker, covering an AT&T label on the main cabinet. 
Over the years the hardware, software, and features were upgraded but the call vectors (scripts) we created in 1999 still worked in 2018.
I was told by an IBM consultant the same was true of our IBM midrange system. (That old commands continue to work on their computers)
Word is a tool I use every single day (on Windows) and it’s a very good product. Unfortunately we still see problems occasionally with people who use it on Mac and send documents. And also those who use ODT as their document format.
For work activities, It’s my go to place for initial ideating and outlining. I also use it for document creation/reviews/updates, and contract reviews.
Clippy 2.0
“You look like you’re writing a letter, can I help?”
Over the last 10 years, MS have become more proactive with removing features from Office applications on major releases (and now as part of ongoing updates) but they tend to do it in a considered way and warn customers well in advance.
With it effectively being SaaS and the requirement to address vulnerability management, customers have less and less options for holding off on updates, so have to roll with it.
What sort of problems? I’ve had zero issues exchanging hundreds of Word docs beck and forth with Windows users (with multiple rounds of revision tracking and comments) since I’ve been using Word on a Mac.
Happy Birthday Word, You have been better than most of the people give you credit for. Its not a joy to use you daily but the hyperbole of 160 characters has been very harsh on you.
Mainly formatting issues, Sometimes weird behaviours around comments and redlines