I admit ignorance so don't slam me for it. Why do folks send files you have to open? Why not just send them already opened?

They probably assume the recipient has the necessary software; a common fault in business and public services.

You or your landlord may have been caught, as I have been, by an insidious wheeze Microsoft and Adobe developed a few years ago. That saves Word and Excel files by default, especially if transmitted, in a special format marked by .docx and .xlsx respectively. Using "zip" compression is just another version of the same trick.

These ".~x" files appear to be similar to .pdf files, so you may be able to read them but no further. A zip file is even worse: it is compressed to save space, but cannot even be read until converted appropriately.

All three types - "x", pdf and zip - are controlled by Adobe, so to convert them to readable and editable forms you need software available from Adobe only, and only by renting it. Over a year that may cost far more than outright purchase, for something you might need only once in a blue moon.

"ZIP! compression was developed so programmes needed less storage space, but I think the un-ZIP software was part of the MS-WIN suite, not something you had to buy or rent separately.

I am afraid it may become even worse, to the point that common software like MS 'Word' and even the operating-system itself (WIN 10 or whatever replaces it) will be by rental only. If so, I think very many users would no longer be able to afford to use a computer or the Internet.