Color Spaces

When one talks about "Color Space", what they are talking about are "Defined Color Spaces".  The main color spaces that are used are:

sRGB

Adobe RGB

&

ProPhoto RGB

sRGB is the smallest color space, Adobe color space is bigger, and ProPhoto is the biggest.

Here is a video that gives you an overview of color space.

https://www.youtube.com/watch?v=KKX08oOTMkk