On Windows – different options:

Print Screen

To capture your entire screen, tap the PrtScn button. Your screenshot will not be saved, but it will be copied to the clipboard — you’ll need to open an image editing tool (such as Microsoft Paint), paste the screenshot in the editor and save the file from there.

Windows Key + Print Screen

To capture your entire screen and automatically save the screenshot, tap the Windows Key + PrtScn. Your screen will briefly go dim to indicate that you’ve just taken a screenshot, and the screenshot will be automatically saved in the Pictures > Screenshots folder.

Windows Key + H

If you’d like to capture your entire screen for sharing purposes, you can use the Windows Key + H keyboard shortcut. This will capture your entire screen and open the Windows Share toolbar so you can immediately share it with your friends via email, Facebook, Twitter, OneNote, etc.

Alt + Print Screen

To take a quick screenshot of the active window, use the keyboard shortcut Alt + PrtScn. This will snap your currently active window and copy the screenshot to the clipboard. You will need to open the shot in an image editor to save it.  

On Mac – different options:

Partial Screen:

1. Press Shift-Command-4.
2. Move the crosshair to where you want to start the screenshot, then drag to select an area.
3. When you’ve selected the area you want, release your mouse or trackpad button.
4. Find the screenshot as a .png file on your desktop (or in Dropbox if you have a Screenshot folder)

Entire Screen:

Or press Shift-Command-3 to capture the entire screen.  

Other tutorial links:

• Here’s a cool website where you can find step-by-step instructions based on your computer. You can also add a website URL and it captures a screenshot of it.
• You can also find a downloadable tool (Lightshot) to capture screenshots here.