Venomous snakes are milked to extract the venom from their glands. The venom is then used in the creation of antivenin. The general process for milking a snake is to place a thin rubber membrane over the opening of a container, and then while holding the snake forcing its fangs into the membrane. The snake will then inject its venom into the container. The handler does not have to force the snake to release its venom, but sometimes they will rub the head to agitate the snake even more. Doing so will often prompt the snake to release more venom than it normally would. After the milking the snake is returned to its enclosure and left alone to produce more venom. This method of harvesting venom from snakes is the only method that is effective.
Milking snakes for their venom is done all of the world using the same method. We should also note that while the snake milker will rub the snake's head to agitate it he or she does not squeeze the venom glands. Doing so can result in the glands being ruptured.