Example: When you are sniping and looking down your scope you see crosshairs...when you shoot your gun while in scope your crosshairs jolt upwards for a very short period...This is called recoil....Many guns have different recoil rates but snipers probably have the largest recoil rate especially bolt action sniper rifles............
Same with all other guns whether it be a pistol or an assault rifle...They all have that "Recoil"...

Understand now mate?

Hope i helped =]