PDF files are readable across all platforms, ie; Mac, Windows, Linux, etc. whether or not you have a photo program on your computer. They're used commonly for documents, flyers, newletters and the like that are sent digitally.
PSD files, I think, can only be read by a photo program. So if you're sending one of your pages to a family member and they don't have the right program, they can't open the file.
To confuse things further, some photo programs can open jpg files but not PSD!
But I don't think it's typical to work in and save things like we're doing here in PDF. I guess if you are planning to create a document and email it, then you'd want to save a copy of it as a PDF so anyone you send it to can read it.
I use it as a way to send newsletters to clients. It compresses easily and without compromising the look of it.
That's the extent of my knowledge on that! I'd love to learn more!
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