The Posting of the Colors is a practice conducted by military color guards of the United States at the beginning of a particular ceremony.
The practice is also done by the Girl Scouts of the United States of America, as well as the Boy Scouts of America.
Posting the colors requires that a color guard team move the colors (usually the American flag, the state flag, the service flag, and the unit flag) from a carried position and placed into a stand.
Specifically, it is done prior to the playing of "The Star-Spangled Banner" or the reciting of the Pledge of Allegiance.
[1][2][3] Media related to Posting the Colours at Wikimedia Commons