Hello,
I’ll talk about a free software I often use to edit my pictures.
It will be very useful if, like me, you need to view large pictures, to crop, rotate, resize them or simply need some organization!
Additionally, it allows to perform several operations on a set of pictures which is very useful when you have to deal with many pictures.
The XnView software available here: http://www.xnview.com exists for Windows. A version for Mac and Linux is under development.

The pictures are displayed faster than the Windows Explorer from which he keeps the same principle panels:
- one panel to navigate within directories,
- one panel for displaying thumbnails,
- and one panel for information with a tab dedicated to the IPTC management in case of JPEG format. The IPTC is used to define a picture with a list of keywords.
The software can display full screen picture with F11 and can also zoom in to the pixel level with the * key. When the screen resolution is lower than that the picture, this key combination is very useful to check that the picture is perfect. This allows to detect artifacts from a too high compression ratio when saving in JPEG format or also to check if the result of a 3D rendering is the one we expected.

When processing multiple pictures you can add a combination several effects: for example, resize and add watermark
You can support its development if you use it regularly.
What software do you use to rework your pictures?
Feel free to leave a comment if you want I detail the usage of this great tool.