Although "photoshop" is often used as a generic term for image manipulation, this tag shouldn't be used unless the question is actually specific to Adobe Photoshop.
Adobe now uses the name to refer to a "family" of products, but common usage and this tag retain focus on the core, original program, which Adobe refers to as "Photoshop CS".
Note that Photoshop questions relating to photo processing are on topic for the site, but general questions on using the software for image editing should go to other Stack Exchange sites http://graphicdesign.stackexchange.com/ or http://superuser.com/.
Comparisons to other post processing software
- Is Adobe Photoshop worth the money?
- What benefit does Lightroom offer over Photoshop + Bridge?
- Lightroom vs. Elements vs. Photoshop: Side-by-side comparison?
- What are the alternatives to Photoshop? Is Gimp a good option?
- What are the key photography-related features from Photoshop that are missing in GIMP?
Resources, tutorials, plugins