I am using Photoshop cs6 for teaching in my computer institute.
Photoshop files have default file extension as .PSD, which stands for "Photoshop Document." A PSD file stores an image with support for most imaging options available in Photoshop.
The handling of color slowly improved with each release from Adobe and Photoshop quickly became the industry standard in digital color editing.
These tools and commands are convenient to combine pixel-based and vector-based images in one Photoshop document, because it may not be necessary to use more than one program.
So Photoshop cs6 is very useful software.