My favorite 4 free photo editor programs
Sure: Photoshop ist great! But it costs you and now Adobe only sells their program as abonnement. You'll be a slave to Adobe for the rest of your life. There are some great alternatives out there. Here are some great stand alone programs. (I use them sometimes in combination with Photoshop.) I am a professional photographer, director of photography and filmmaker. And I love these. They are fun to work with. But: most of them do not have layers or masks.
PhotoScape.org (free): edit, make collages, gifs, filter effects. realy easy. I love making collages with that program (see photo collage of my visit on open day to the Refugium Beelitz Creative Village project)
LightZoneproject.org (free): digital darkroom, raw and all formats, effects, compare to lightroom.
Perfect Effects 8 Free Edition: good for vignettes, film look, bloom effects. etc. you can use it as plug-in to Photoshop, Aperterure, etc. Works with layers. (You can buy the full version and you'll get a pretty good stand alone editor.)
PicsArt.com (free) for mobile, ipad: the best and diverse mobile app. to photo edit. extensive effects, texts.
Check them out yourself!