From The Art and Popular Culture Encyclopedia
An aide-de-camp (French for camp assistant) is a personal assistant, secretary, or adjutant to a person of high rank, usually a senior military officer or a head of state. The first aide-de-camp is typically the foremost personal aide.
In some countries, aide-de-camp is considered to be a title of honor (which confers the post-nominal letters ADC), and participates at ceremonial functions.
The badge of office for an aide-de-camp is usually the aiguillette, a braided cord in gold or other colours, worn with a uniform on the left (or sometimes right) shoulder.