Since at least Windows 7, Windows has had a Snipping Tool. I've always accessed it by pressing the Windows key and typing "snipping". Or you can press Windows key + Shift + S, then drag your cursor over a portion of the screen to capture it. The Snipping Tool had some simple mark-up tools.
In Windows 10 1809 the Snipping Tool is still there but there's a new Snip & Sketch UWP app. Pressing Windows key + Shift + S brings up a small toolbar with icons let you capture a rectangular portion of the screen, the entire screen, or a freehand-drawn portion of the screen.
If you click on the notification you'll see the UWP app with the editing tools.
These are much more capable than those in the pre-1809 Snipping Tool.
It's simple but certainly a nice improvement.