Jägers are light infantry, trained for action in small groups or independently. Jägers are usually considered elite troops. Modern Jägers can for instance be paratroopers.

Jäger is German for hunter, and the Jäger troops were originally recruited from among the huntsmen and foresters. They were often of what, with a modern term, can be considered middle class backgrounds, often belonging to the lesser nobility. Jäger troops were first organized in the 18th century, when also some Jägers participated in the American War of Independence. They were most often used as screening forces or as reconnaissance troops.

As their weapons were private, they could (at least in theory) fill a crucial defensive role in case of surprise assaults before any mobilization had been ordered, or as organizers of partisan warfare after an occupation. Jägers are often excellent snipers able to inflict heavy casualties among enemy officers. Their ability to lay exceptionally accurate rifle fire made them a good support for vulnerable troops, as for instance engineers constructing forward trenches.

For fights in close quarters the Jäger carried a straight-bladed small hunting sword (Hirschfänger), or alternatively a small curved blade hunting sword, or perhaps a falchion.

Jägers became more popular after the Napoleonic Wars, when volunteers of bourgeois background were organized for the resistance against Napoleon's occupation. Continuing the earlier traditions, these Jägers were patriotic volunteers, carrying the costs for their weapons and uniforms by their own means—or with the help of contributions from friends and neighbours, often organized in clubs and leagues. The resistance against Napoleon's troops exacted a high toll, not the least among the officers, which is why plenty of soldiers were promoted to officers. At the end of the war most of the lower officers were promoted Jägers.

See also: Finnish Jäger troops, infantry, army, military history, military science; see Jaeger for other uses of the term.