A side boy is a member of an even-numbered group of seamen

Seaman

Seaman is one of the lowest ranks in a Navy. In the Commonwealth it is the lowest rank in the Navy, followed by Able Seaman and Leading Seaman, and followed by the Petty Officer ranks....

 posted in two rows at the quarterdeck

Deck (ship)

A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary deck is the horizontal structure which forms the 'roof' for the hull, which both strengthens the hull and serves as the primary working surface...

 when a visiting dignitary boards or leaves the ship

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

, historically to help (or even hoist) him aboard, presently as a ceremonial guard of honour, in a ceremony known as tending the Side. Side boys are instructed by the piping

Boatswain's pipe

A boatswain's call or pipe is a pipe used on naval ships by a boatswain. It is pronounced, and sometimes spelled, "bosun's call".The pipe consists of a narrow tube which directs air over a metal sphere with a hole in the top. The player opens and closes the hand over the hole to change the pitch...

 of the Boatswain

Boatswain

A boatswain , bo's'n, bos'n, or bosun is an unlicensed member of the deck department of a merchant ship. The boatswain supervises the other unlicensed members of the ship's deck department, and typically is not a watchstander, except on vessels with small crews...

's Mate. The Quarterdeck being a ceremonial location on a weatherdeck of the ship, usually at the location of the accommodation (boarding) ladder

Accommodation ladder

An accommodation ladder is a portable flight of steps down a ship's side.Accommodation ladders can be mounted parallel or perpendicular to the ship's board. If the ladder is parallel to the ship, it has to have an upper platform. Upper platforms are mostly turnable...

 or brow.

Since 1843, United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 regulations have stipulated the number of Side boys according to the protocollary importance of the guests, which are similarly entitled to other honors; viz., the tune and number of ruffles and flourishes

Ruffles and flourishes

Ruffles and flourishes are preceding fanfare for honors music .Ruffles are played on drums, and flourishes are played on bugles...

 and the number of cannon fired as a salute

Salute

A salute is a gesture or other action used to display respect. Salutes are primarily associated with armed forces, but other organizations and civil people also use salutes.-Military salutes:...

. The side boy function may be performed by either male or female members of the ship's complement.