The significance of the guidon is that it represents the unit and its commanding officer. When the commander is in, his guidon is displayed for everyone to see. When he leaves for the day, the guidon is taken down.
It is an honor to be the guidon carrier for a unit, known as a "guidon bearer". He or she stands in front of the unit alongside of the commander, and is the rallying point for troops to fall into formation when the order is given. In drill and ceremonies, the guidon and commander are always in front of the formation.
The guidon is a great source of pride for the unit, and several military traditions have developed around it, stemming back from ancient times. Any sort of disgrace toward the guidon is considered a dishonor of the unit as a whole, and punishment is typical. For example, should the guidon bearer drop the guidon, he must fall with it and perform punishment, often in the form of push-ups. Other units may attempt to steal the guidon to demoralize or antagonize the unit. Veteran soldiers know not to give up the guidon to anyone outside their unit, but new recruits may be tempted into relinquishing it by a superior, especially during a unit run.
Each branch of the U.S. military has their own customs and procedures.....
As described in Chapter 6 of Army Regulation 840-10, guidons are swallow-tailed marker flags in branch-of-service colors, measuring 20 inches at the hoist by 27 inches at the fly, with the swallow-tail end forked 10 inches. Old guidons show letters and numerals reversed as if printed through on the reverse of the guidon. Current guidons are made so that letters and numerals read correctly on both sides.
A Marine guidon is always rectangular, 22 by 28 inches, with a scarlet field and gold lettering, and an Eagle, Globe, and Anchor centered.
Recruit training units do not have any branch of service indication on their guidons; boot camp platoon guidons only display the platoon number in yellow/gold against a scarlet background. During the first phase of training, the guidon's foreground and background colorations are exchanged, yielding a red platoon number against a yellow/gold background
Navy ships and squadrons may display a unit guidon while parading ashore. It measures 20 1⁄8 by 27 3⁄4 inches with a 10 inches swallowtail, is blue with white text, and depicts a fouled anchor within a diamond. Prior to World War II, a red flag was used for naval artillery units. In addition, companies of the Brigade of Midshipmen attending the United States Naval Academy utilize a gold guidon with blue numerals.
In the Air Force, guidons are ultramarine blue wool and nylon, nylon, or polyester bunting, 20 by 27 inches to end of the swallowtail, and forked 10 inches. An Air Force yellow American Eagle design appears on the front of the guidon and on the reverse side as if printed through. Above the design is the designation of the parent unit; below it is the designation of the squadron. When the number of the squadron and the parent organization are the same, the lower line indicates only the alphabetical portion of the squadron designation. Numerals and lettering are yellow, from 1 3⁄4 by 3 1⁄2 inches tall, and in varying widths. Lettering and numerals appear on both sides of the guidon, reading from left to right on both sides
And there you have it. Now you know what a guidon is, and how it works. Not a bad way to start a Monday.....