A marching band is a group of instrumental musicians who perform while marching, often for entertainment or competition. They are most popular in the United States, though not uncommon in other parts of the world. Instrumentation typically includes brass, woodwind, and percussion instruments. Most marching bands wear a uniform, often of a military style, that includes an associated organization's colors, name or symbol. Most high school marching bands, and some college marching bands, are accompanied by a color guard, a group of performers who add a visual interpretation to the music through the use of props, most often flags, rifles, and sabers.

Marching refers to the organized, uniformed, steady walking forward in either rhythmic or route-step time; and, typically, it refers to overland movements on foot of military troops and units under field orders. Marching is often performed to march music and is typically associated with military and civilian ceremonial parades. It is a major part of military basic training in most countries and usually involves a system of drill commands.