Also photoscape seems nice. That's the one with the circle crop...

Gimp is more complex for more controls many people use it and like it.

You can often find free copies of Adobe Elements which came free with cameras and printers years ago. It's like Photoshop Lite.

Depends on what you want to do? If it's basic corrections to lighting, crop and resize:

I still say Irfanview is the best working free photo editing software, overall. http://www.irfanview.com/ don't miss the plugins part because it adds features. Also will run any 8BF filter that is designed for Photoshop if you should want filters, editing, sharpen, conversion, paint and other things.

FREE 100% free, no demo, trial or crippleware tricks.