I participated several times (nerve wracking but proud moments) and was curious about the history:
From the Wiki:
In the military of the United States and other militaries, the color guard (where the word color is referring to the US flag) carries the National Color and other flags appropriate to its position in the chain of command. Typically these include a unit flag and a departmental flag (Army, Marines, Navy, Air Force, or Coast Guard). In addition to the flag bearers, who are positioned in the center of the color guard, there are two individuals who carry rifles.
Since early history, flags and banners have been used by many armies in battle. They served several purposes: to identify units, for signaling and to be a common point of reference for the movements of the soldiers in the unit, enabling them to keep formation. The flag was also a symbol of the unit. The loss of a unit’s flag was not only shameful, but losing this central point of reference could make the unit break up. To protect the flag, a detachment of soldiers was assigned to guard it.
The Swedish military rank of fänrik (and the corresponding cavalry rank of kornet) was originally intended for the holder of the company flag. This duty was so prestigious that an officer was necessary to carry it out, but it required no officer training. Today, it is a regular officer rank.
Composition of the US color guard
In the U.S., traditionally, the unit’s sergeant major is responsible for the safeguarding, care, and display of the organizational colors. The sergeant major is also responsible for the selection, training, and performance of the members. The color guard consists of enlisted members and is commanded by the senior (color) Sergeant, who carries the National Color and gives the necessary commands for movements and rendering honors during drill exercises or parade ceremonies.
Being assigned to the color guard is considered an honor due to the fact that these individuals present and carry the symbols of their unit and country. Depending on the circumstance and subject to the orders of their commander, members may wear full dress or less formal uniforms. It is mandatory for all members of the color guard to wear headgear, for example, a garrison cap, beret, or service cap. On occasion, certain color guards can be horse–mounted.
It’s a time honored tradition and I remember when I was able to hold the colors I had such a sensation of pride…difficult to describe but was so proud knowing I became part of this historical tradition.