how to backup all pictures without itunes

My mother's iPhone has collected over 1000 family pictures from the camera, emails and whatsapp. I am definitely NOT an Apple guy and I don't know where to even begin.

I'd like to save all the pictures on my computer and delete them off the phone. This will help me backup the pictures + create space on the iPhone.

What is the best, easiest and fastest way to do this without installing iTunes?

I do not have a MacBook or any laptop with Apple operating system on it. I do have an iPad though.