Profiles are closed loops that define cross sections for sketch-based features. A circle is always a profile, and a series of lines and curves form a profile when all of the end points connect. Some feature commands, like Extrude and Sweep, require a sketch profiles.
Sketch profiles are automatically detected and displayed as shaded regions. If two profiles overlap, the additional region is recognized as a separate profile.
In the following image, the sketch profiles are shown in yellow. The blue rectangular region under the cursor illustrates a selected profile.

If the end points of two sketch entities are close, but not connected, they display in red. This simplifies diagnosing the sketch to find out why a profile is not recognized as a region.
