How to transfer photos from iPhone to desktop?

My phone doesn't have any capacity left so I want to transfer all my 2000+ photos which takes up 3+GB to my desktop and delete them from my iPhone but I can figure out how: /
Teach me!

USB wire.

You need to install iTunes to your desktop and then with the help of USB cable you can transfer the photos from iPhone to desktop.

Merry Xmas. If you mean the iPhone camera pictures, Connect your iPhone to computer through USB cable, and then open 'My computer', click on what should say 'Apple iPhone' (possibly have a picture of a camera next to it). And then go to folder 'Internal Storage -> DCIM -> 800AAAAA'. You should find all your pictures and videos that you recorded with your iPhone.
For Mac user, you can use iPhoto to transfer the camera pictures.

If you mean the photos that you sync from iTunes. You may refer to this step by step guide, it's about how to copy photos from iPhone/iPod back to computer. It's easy to understand and works pretty well for my iPhone.
http://www.ipod-transfer-copy.com/guides/copy-ipod-photos-to-computer.html
Hope it helps. Contact me if you have any other question.