Firefox has a built-in tool for taking screenshots. It is indeed intended for content that is displayed in the browser, but no less useful for that!
Firefox is a great and modern browser. At the moment it is actually only one of the few real alternatives, especially now that Edge is switching to Chrome's engine. Furthermore, Firefox has a handy extra on board in the form of a screenshot maker. This allows you to capture displayed web pages as images. Of course you could use the PrintScreen key for that, but it has the disadvantage that only the visible part of the page is captured. With the tool in Firefox you can - if you wish - save the entire page as an image. Sometimes this is practical, for example if you want to use the page as an illustration in an article or report. But also some web pages simply cannot be printed (decently). In that case, saving as screenshot may be an option. Certainly if the resulting image is not too 'long', a print can still be made in this way. Or cut these in a photo editor into smaller chunks that you then print one by one. Anyway: that tool is not so crazy after all!
To work
To take a screenshot of an open page in Firefox, right-click anywhere on this page. In the opened context menu - just left click - on Take a screenshot. You can now record a number of things. Move your mouse over the page and choose one of the elements to save as an image. Or click Save visible area for a more or less regular screenshot containing only the part of the page shown in the window. To really capture the entire page from top to bottom as an image, click on the button Save full page. You can now choose from a number of actions. You will see the preview of the captured page with a few buttons above it. If you change your mind and do not want to use the image, click on the cross. To paste an image directly into, for example, a photo editor or word processor, click on the copy button (and then click on paste in the other program). If you just want to save the image in a folder, click the download button. Saving in the cloud is also possible, via a click on Save. This makes it possible to share an image with others. In that case, it is wise not to save screenshots with privacy-sensitive information in this way. After all, you never know who may or may not accidentally get away with it. By the way, the whole screenshot tool is (for quite some time) in beta stage. You may also run into a glitch here or there. But experience shows that fortunately it is not that bad.