A sniper is usually a highly trained marksman that shoots targets from concealed positions or distances exceeding the capabilities of regular personnel. Snipers typically have specialized training and distinct high-precision rifles. In addition to marksmanship, military snipers are also trained in camouflage, field craft, infiltration, reconnaissance and observation techniques.

Etymology

The term sniper was first attested in 1824 in the sense of the word 'sharpshooter'. The verb 'to snipe' originated in the 1770s among soldiers in British India where a hunter skilled enough to kill the elusive snipe was dubbed a "sniper".

During the American Civil War, the common term used in the United States was 'skirmisher'. Throughout history armies have used skirmishers to break up enemy formations and to thwart the enemy from flanking the main body of their attack force. They were deployed individually on the extremes of the moving army primarily to scout for the possibility of an enemy ambush. Consequently, a "skirmish" denotes a clash of small scope between these forces. In general, a skirmish was a limited combat, involving troops other than those of the main body. The term 'sniper' was not in widespread use in the United States until after the American Civil War.

In the last few decades, the term 'sniper' has been used very loosely. Gun control advocates used this term so loosely that some people even called it sniping when a handgun was used; the term 'sniper rifle' was considered very "scary sounding" and was very effective in inciting fear, evoking a lot of unsettling images, such as "a lone gunman, undetectable, on the hunt".­

The term 'sniper' has been used in more serious tones especially by media in association with police precision riflemen, those responsible for assassination, any shooting from all but the shortest range in war, and any criminal equipped with a rifle in a civil context. This has rather expanded the meaning of the term. It has also given the term 'sniper' mixed connotations. Official sources often use more positive connotative terms to describe snipers, especially for police snipers: 'counter-sniper', 'precision marksman', 'tactical marksman', 'sharpshooter', 'precision riflemen', and 'precision shooter'. Some of these alternatives have been in common use for a long time; others are closer to undisguised euphemisms.

Snipers in warfare

Different countries have different military doctrines regarding snipers in military units, settings, and tactics. Generally, a sniper's primary function in warfare is to provide detailed reconnaissance from a concealed position and, if necessary, to reduce the enemy's fighting ability by striking at a small number of high value targets (especially officers, communication and other personnel) and in the process pinning down and demoralizing the enemy.