Photoshop doesn
Photoshop more than supports many color spaces; it supports infinite variations on the device-dependent ones. You can open an RGB photo, process it in Lab, and output it to CMYK, with certainty that each conversion will work.
The
The ubiquitous eyedropper is simple in purpose and easy to use. But imagine a world without it, where you had to dial in every one of the 16.8 million+ colors manually. The eyedropper is Photoshop
The Levels command, and its cohort the histogram, let you adjust luminance levels on a channel-by-channel basis. The upshot is that you can increase contrast, correct for color cast, and make a bad image good.
The Color Settings command is your way of establishing reliable color management policies across the entire Creative Suite. While admittedly techy, it ensures that what you see is what everyone else sees as well.
Changing the Opacity is like mixing a cocktail with, say, 25% active layer and 75% all layers below. Assigning a blend mode is like shining a light or casting a shadow: The active layer infuses those behind it with life.