The color guard are the group of marchers who spin and catch flags, rifles, and sabers. Guards most often have a special uniform or costume that is distinctive from that of band, and may or may not match each other.
In a marching band or a drum & bugle corps, the color guard is a non-musical section that provides additional visual aspects to the performance. The marching band and color guard performance generally takes place on a football field while the color guard interprets the music that the marching band or drum & bugle corps is playing via the synchronized spinning of flags, sabers, shields, or other pieces of equipment, or through dance.
In drum and bugle corps, there used to be a requirement for a traditional presentation of the colors during the competitive show (called the "Color Pre"), but this fell out of favor around the early 1970s. A recent example of a color pre in show was the 2002 San Francisco Renegades Sr corps, used during "America the Beautiful" to open their program, but shc a presentation was NOT a required part of the show.
Junior corps almost never have a traditional color guard (commonly called the "A squad") today, but most, if not all of the all-age corps have one, ranging from one to carry the US flag and one to guard it, to A squads almost as big as a small corps! These units typically stand in the side 2 (audience right) front sideline at the end zone, facing away from the performing unit to protect the colors from outside threats.