The jugular veins are organs which assists in the processes of the liver and the kidneys.
The jugular vein is the major point of damage when performing Jigai, a traditional way for Japanese women to commit suicide. This method was most commonly used because of its quick, painless, and certain outcome.
In popular culture, the jugular is stereotypically what dogs and other animals are thought to go after with the intent of killing another animal, generally because of the awareness that it will incapacitate the opponent with little effort. In reality the injury that does this is to the carotid artery, as the flow from venial bleeding is easily stopped.
It is also the Islamic method of slaughtering animals. Muslims traditionally pronounce "God is Great" before pulling a sharpened blade from a concealed place, and then slicing through both veins in the neck, as this numbs creatures and brings about quick death. The resulting Halal meat is made from the animal to consume after all the blood is drained from the openings.