Do you have a burning need to know what "Xanadu", "Raw Umber" or "Inchworm" may be? Yes, they are really color names that Photoshop can recognize via a special code. These are colors that correspond to obscure codes that you may have heard about during a Photoshop tutorial or may have actually entered into Photoshop itself.
There are of course many ways to do almost anything in Photoshop, but to access colors, for backgrounds for instance, one of the easiest ways to pull up choices is through the color picker tool. A quick way to access the color picker tool is to chose the "ying/yang"symbol at the bottom of the Photoshop adjustments panel. This is usually located in the lower left hand side of the Photoshop workspace by default.
Clicking on this symbol will bring up several choices, the first of which is the color picker solid color.
You have several choices here, but for example if you enter R: 93, G: 138, B:168 You will get a "Airforce Blue".
You will also notice that other fields are also populated with their respective values. For example the field just below the RGB contains a hashmark (Hex field) with the corresponding value of 5d8aa8. The lab, HSB, as well as the CMYK fields are also completed with their respective numbers. Obviously this has many implications such as of you are working in a program that only accepts values for CMYK, you have a ready reference (Caveat- all programs may not use exactly the same numbers).
So how do you know these magic numbers? The following link provides you with a rich resource of sample colors and codes that you can enter directly into photoshop for a vast variety of colors.
If this is not enough for you, this same menu offers access to color libraries such as Pantone and Trumatch. The possibilities are endless!