A marksman is mostly to be found in a military context. He/she is trained to shoot precisely with a certain type of rifle. Some military doctrines use marksmen attached to an infantry squad. In that capacity the marksman takes accurate longer range shots at valuable targets as needed, thus extending the reach of the squad.

Another term for a marksman is a sharpshooter.

A marksman should not be confused with a sniper. While snipers are intensively trained to master field craft and camouflage, these skills are not required for marksmen. There are differences in role and training that affect doctrines and equipment. Snipers rely almost exclusively on stealthy bolt-action rifles while a marksman can effectively utilize a faster-firing, but more conspicuous semi-automatic rifle. A sniper's intensive training, forward placement and surveillance duties make the role more strategic than a squad-level marksman. Thus, marksmen are often attached at the squad level while snipers are often attached at higher levels such as battalion.

In the British Armed Forces, marksman is traditionally the highest shooting rating. Holders of the rating wear a crossed rifles badge on the lower sleeve.

One of the first true appearances of units of sharpshooters was during the Napoleonic era, in the British Army. While most troops at that time used inaccurate smoothbore muskets, the British "Green Jackets" (named for their distinctive green uniforms) utilized the famous Baker rifle. Through the combination of a leather wad and tight grooves on the inside of the barrel (rifling), this weapon was far more accurate, though slower to load. The Rifles were the elite of the British Army, and served at the forefront of any engagement, most often in skirmish formation, scouting out and delaying the enemy.

During the American Civil War (1860–1865), sharpshooters saw limited action, as tacticians sought to avoid the heavy casualties inflicted through normal tactics, which involved close ranks of men at close ranges. The sharpshooters used by both sides in the Civil War were less used as snipers, and more as skirmishers and scouts. These elite troops were well equipped and trained, and placed at the front of any column to first engage the enemy. The most notable sharpshooter units of the Civil War were the 1st and 2nd United States Sharpshooters (USSS), who were formed from all states under the command of Hiram Berdan, who was the best amateur marksman in the nation at that time. Confederate sharpshooters were often less well equipped, using British Whitworth rifles , rather than breech loading Sharps rifles .