Paint.net is a free, downloadable, image and photo editing software for Windows. It is easy to use, has a ton of features like layers, special effects and more, and a great community for help and ideas.
It is easy to use, but powerful enough for most people's needs. It is a great tool for editing images and a great, free replacement for Photoshop, Paint Shop, and others. It's also easier to use than some of the other free editing software like GIMP.
