What exactly does the margin refer to when printing?

Hey, I've built an app, that draws text to four rectangles on a pre-printed page with a design, I'm wondering what the margin refers to?

I've not specified any margin...

Also our printer doesn't print all the way to the edge, there's a white border, about the height of this little guy: :),

If I printed from a printer that prints to the edge, will the text be in the same position as it would be if it was printed with the border around it, the text should be in the exact same position right?

Kind Regards
Me

Printer Margins and Printable Area Size are determined by your printer's mechanical limitations. The printable area may be positioned anywhere on the paper, as determined by the mechanics of your printer.

You may notice that when you print Portrait the printable area has a small margin at the top and large margin at the bottom versus printing in Landscape mode which will have a tiny margin on the left edge while the right edge has a large margin.

Also keep in mind that most printers cannot print to the very edge of the paper. Unless your printer specifies that it has borderless printing capability, it probably can't do it. And, even if the specifications say the printer can do borderless printing, bugs in its printer drivers are not unheard of.

The way the page is printed is normal, not landscape, it's an a4 sheet of paper with a design printed on it (not by us), my app fills in several blank boxes on the page, I've tested, improved, tested improved etc.. until they are in the correct position.. our printer does not print to the edge, the clients printer does, I'm wondering if my positioning of stuff is going to be off, because theirs prints to the edge...

Like, when I draw on the page, is the page dimensions always the same, or is it a little smaller/larger, depending on whether the printer can print to the edge?

Does that make sense?

Kind Regards
Me