How to reformat a SD Memory Card

…And Why?
So, I typed in “how to reformat sd card” into Google, and the first bit of info that pops up is here:

Sadly, I couldn’t work out how to open Disk Utility.  Foiled at step 2 isn’t a great start!
So, in Windows Explorer, if I right click on the USB drive, it reveals a drop down menu.   Select Format.  Then hit Start.  
It comes up with a WARNING – IT WILL ERASE all data on the memory card.  I hastily copy over 650 photos into a new location and then delete them from the memory card…So, now I hit Format, and quick as a flash, “Format is Complete”.
But what’s the point?
Well, if you just delete images from your SD card, you don’t completely remove all the surrounding data.  Even though it looks clear to you, there is residual data left behind that will eventually build up over time.  By formating your card, this erases all the “hidden” bits and bobs, providing more storage for your images and hopefully reducing the chances of data corruption.
But just to reiterate, always ensure your images are safely backed-up before attempting to re-format…as Pringles have discovered, once you start,  you can’t stop, unless you have some special software to recover the loss.
UPDATE – so if you’re a software engineer like my husband, he doesn’t agree with the contents of this blog.  We had a small debate…He’s going to tell me why I’m wrong later.  What fun.
I found this website www.digitalcameraworld.com and the quote below is from the following article:
https://www.digitalcameraworld.com/features/what-actually-happens-when-you-format-a-memory-card

Does formatting a memory card delete its contents? 

No – at least, not quite. Formatting a memory card gets rid of any existing folder structure that was set up from previous use, and refreshes it with a new one that’s specific to the camera you’re using. So, you won’t be able to access those images and videos through your camera, or through the normal way you would on a computer, as those folders are no longer there.

The information on the card, however, may still be retrieved using image-recovery software. That’s because it’s still on the card, just not within the same folders as before. This is great news if you’ve accidentally deleted images or formatted a card that you intend intend to format, but there’s no guarantee that you will be able to get these back successfully.