The M16 is a lightweight, air-cooled, gas-operated rifle that was first introduced in the 1960s. It became widely known as the standard infantry weapon for the U.S. military during the Vietnam War. The rifle is designed for accuracy and has a high rate of fire, making it effective in various combat situations. Over the years, the M16 has undergone several upgrades and modifications, leading to different variants. It typically uses a 5.56x45mm NATO cartridge, which allows for manageable recoil and improved control. Today, the M16 remains in use by some military forces and is recognized for its reliability and performance.