A marching band is a group in which instrumental musicians perform while marching, often for entertainment or competition. Instrumentation typically includes brass, woodwind, and percussion instruments. Most marching bands wear a uniform, often of a military style, that includes the associated school or 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 and rifles.

Marching bands are generally categorized by function, size, age, gender, instruments, and style of show they perform. In addition to traditional parade performances, many marching bands also perform field shows at sporting events and at marching band competitions. Increasingly, marching bands perform indoor concerts that implement many songs, traditions, and flair from outside performances.