A working space is an intermediate color space used to define and edit color in Adobe applications. Each color model has a working space profile associated with it. You can choose working space profiles in the Color Settings dialog box.
A working space profile acts as the source profile for newly created documents that use the associated color model. For example, if Adobe RGB (1998) is the current RGB working space profile, each new RGB document that you create will use colors within the Adobe RGB (1998) gamut. Working spaces also determine the appearance of colors in untagged documents.
If you open a document embedded with a color profile that doesn’t match the working space profile, the application uses a color management policy to determine how to handle the color data. In most cases, the default policy is to preserve the embedded profile.