[signal11]

Firefox's DevTools can render a whole web page as an image to disk (not just the visible viewport, like screenshot tools do). Quite a few non-developers have found that useful when I've showed this feature to them. No extensions or 3rd-party software required.

[acqq]

I don't know about that too, how can I do it?

[signal11]

Press Shift-F2 and at the prompt type "screenshot --clipboard --fullpage" to copy the current page to the clipboard.