Color space is an abstract mathematical model used to describe how colors can be represented ( to paraphrase wikipedia). It can be the cause of much frustration when using images for print or web output.
This article is a brief run down on the terms followed by some tips on how to manage color on a separate post.
A good analogy is a musical score. A piano, guitar and ukulele are all capable of producing musical notes. We use musical notation to describe those notes on a page. If we use a score play a tune on a piano. The guitarist or ukulelist can also play the same tune using the same score ( without hearing it first). The principle is that there is a code for the frequencies of sound.
Color space is similar in this way, if i take a photograph with a digital camera, we use the color space model to transcribe or translate the colors values recorded in the camera to their representative color values on a monitor or another digital device. The principle is that there is a code for the frequencies of light.
To continue with our musical analogy , the translation of tunes between instruments is transposition. In an ideal world all instruments would be able to play every note. In the real world a piano has more notes than a guitar, and a guitar more than a ukulele. What do I do if I want to play a tune that is out of the guitars range of notes. I have some choices I can transpose the harmony and the melody to the pitch of the guitar, or I dispense with the harmony and choose the play the melody only.
Color space models are used to “transpose” the range of colors from one device to another. For example: from a digital image to a printed poster. If I want to print that image the color space model is used to “transpose” the color values from the camera into a print.
Gamut refers to the amount of colors within a color space model. It is similar in idea to pitch range. When we translate the colors from a camera image to a print it is similar to the transposition of a tune from piano to guitar.
In many instances the range of colors available in the image will exceed the color range of the print. In general this is not problematic, as long as the transposition is correct.