Comments are a way to make RPM ignore a line in the spec file. The contents of a comment line are entirely up to the person writing the spec file.
To create a comment, enter an octothorp (#) at the start of the line. Any text following the comment character will be ignored by RPM. Here's an example comment:
# This is the spec file for playmidi 2.3...
Comments can be placed in any section of the spec file.