Colorguard has changed a lot over time. Originally, colorguard were soldiers responsible for bearing the flags of their nations and units in battle. This is far from the modern colorguard.
The modern colorguard is an integral part of a marching band. They provide movement and expression not permitted with carrying instruments. Whether through dance or the use of flags, the colorguard helps heighten the emotion of the audience.
The colorguard is no longer gender specific, though the majority of guards are female. Since it was once a military battle tradition, the colorguard was only male. Today a well known exception is the drum corps “The Cavaliers”. They are an all male drum and bugle corps that competes in the DCI circuit. Other corps, like “The Cadets of Bergen County” are diverse.
In high schools, colorguard’s role has increased as much as the more competitive circuits. High schools seem to be grooming their musicians and performers for bigger and better things, so it’s better to learn the skills early and have an edge should you decide to move on to the competitive divisions.