The idea was that the document was an exact, unchangeable copy of the original (while some PDFs can now be edited, you can create a PDF that cannot). In case you’re not familiar with the background of that format, PDF stands for portable document format and was created by Adobe in the early 1990s to allow people and organizations to create exact digital versions of paper documents.
Now that so many people are working remotely, it’s become more accepted than ever for official documents to be sent digitally - and most are sent as PDFs.
