A sniper is a marksman who 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 trained in camouflage, field craft, infiltration, reconnaissance and observation. Snipers are especially effective when deployed within the terrain of urban warfare, or jungle warfare.

They use a special rifle that can shot long distance.
Phenomen started in gaming .I think in cs…
When you are killed by a sniper you can even "rage quit".
The most annoyng thing on snipers is the camouflage.
Most of them stand in same position becouse if they move they can get killed.
How i already say they use the distance for protection so if you run for them…
Many people use rifle becouse is easy to use and hard to detect.
A notable thing is that:the snipers have slow recarghing and most of them only shot 1 bullet.

P.S If you wanna say something about my grammar…Don't say becouse i am a 12 years old kid that live in romania O_O.
also first informations are from wikipedia >.>.