Often you need to get a copy of your screen or a part of it for documentation purposes. There are many different ways available with Windows 10, my two favourite tools are mentioned here, they also give you some choice on what part of the screen you want to copy.
This tool is around already for a long time. It will not show up any more as an app, so you will need to type its name in the search bar at the bottom of the screen. Then you can choose it.
Click the New button to begin the screenshot process. The default snip type is a rectangular snip, but you can also take free-form, full-screen and window snips.
The Snipping Tool does not automatically save your screenshots -- you will need to manually save them in the tool before you exit -- and it does automatically copy your captures to the clipboard.
This tool maybe discontinued in the future, a message with that content will be displayed when you launch the app.
Snip & Sketch
This is a newer tool, the fastest way to launch it with the keyboard shortcut Windows key + Shift + S. You will also see the Snip & Sketch tool listed in the Start button as well as in the notification panel where it is listed as Screen snip, these are two alternative ways to start the app.
After launch, the screen will be dim and a tiny menu will open at the top of your screen. It lets you choose which type of screenshot you want to take -- rectangular, free-form, window or full-screen.
Once you take your screenshot, it will be saved to your clipboard. Click the notification that pops up to open the screenshot in the Snip & Sketch app to process it further in the app. You may also access the image via the notification panel.
There are other options. available with this tool, just have a look in the documentation.
Both these tools are not as powerful as some commercially available tools, but they give you the basic functionality and they are free-of-charge.