Go to https://getsharex.com/ and download the latest version of the program.
Install the software by following the prompts.
(Tick 'Run ShareX when Windows starts' and 'Show "Upload with ShareX" button in Windows Explorer context menu')
Now, when you open the main window, you will see this

Click on 'Hotkey settings...'

Modify the hotkeys to your preferred setup, our recommended hotkeys are below, though you may wish to disable all except Capture region (press Escape to disable a hotkey) so you don't accidentally get things you don't want

Open the "After capture tasks" menu

Make sure these are highlighted:
C:\Users\[username]\Documents\ShareX)
Now you're ready to take screenshots!
When you press your keybind, you will be able to select the region you want to capture by click & dragging!

Once you make your selection, the image will be opened in the image editor, where you can quickly add text, arrows, highlight, blur, or make any slight adjustments.

Now press Enter and we are done!
The image is now in your clipboard - you can quickly send it to friends via Discord by pressing Ctrl + V into the chat box! The file is also stored in C:\Users\[username]\Documents\ShareX.
Don't worry - these do not take up much storage space at all, so take as many screenshots as your heart desires!
ShareX also has tons of other cool features, like capturing GIFs, screen recording, uploading straight to image sharing sites with a single click and more! I suggest you play around with it once you get comfortable. It's really awesome!
⇧ + ⌘ + 4 (Shift + CMD + 4)⇧ + ⌘ + 5 (Shift + CMD + 5) to open the Screenshot appRecord Selected Portion option as shown below
⌘ + ⌃ + Esc (CMD + Control + Escape) or click the Stop button in the menu barFor more information about taking screenshots/video on Mac OS, see Apple's information pages for screenshots and videos