Taking a snapshot is when you want to "take a picture" of what is on your computer screen. It is a very helpful tool to use especially if you want to show when an error has occurred to easily explain how it happens and what it looks like.
For Microsoft Computers
If you are using a Microsoft computer then there is a tool called the SNIPPING TOOL. If you do not know how to find this tool you can do a quick search in the search dialogue box to easily find it. It looks like this:
If you click on the "New" button it will automatically choose a rectangle for you to use as a selection tool for you to copy or "cut". You then chose the perimeter of the rectangle you want to copy by clicking the spot you want start from and leaving your finger on the left click button of your mouse (the main button you use depending on if you are left or right handed) and dragging the mouse outwards then releasing the button when you have selected the area. Alternately, you can click on the down arrow next to the new button and selecting from either the prepopulated sizes or freestyle sizes.
Then go into your email or paint or PowerPoint depending on the application you want to save it in and right click (again opposite for lefties) and select paste or the shortcut CTRL V.
Alternatively, some keyboards have a PrtScn button which means print screen which copies the whole screen you are working on. The process for pasting and saving is the same as above.
For Mac Computers
If you are using an Apple device you press "Shirt", "Command" and "3" at the same time,
Use Command + V or Edit > Paste to paste your image. Your screenshot image can be pasted straight into any compatible application, such as a Word document, an image editing program, and many email services.