Fusilier is a name given to various kinds of soldiers; its meaning depends on the historical context. While fusilier is derived from the 17th-century French word fusil – meaning a type of flintlock musket – the term has been used in contrasting ways in different countries and at different times, including soldiers guarding artillery, various elite units, ordinary line infantry and other uses.

Light infantry refers to certain types of lightly-equipped infantry throughout history. They have a more mobile or fluid function than other types of infantry, such as heavy infantry or line infantry. Historically, light infantry often fought as scouts, raiders, and skirmishers. These are loose formations that fight ahead of the main army to harass, delay, disrupt supply lines, engage the enemy's own skirmishing forces, and generally "soften up" an enemy before the main battle. Light infantrymen were also often responsible for screening the main body of a military formation.