The most common material from which tea bags are made is filter paper. Filter paper is usually made of abaca, the leaf stalk of a banana plant from the Philippines.
Most mass-produced tea bags are made in an assembly line. Two large rolls of filter paper are fed through a machine that releases dried tea leaves between them. A conveyor belt then brings the paper and tea into a drum, which seals them shut with an indentation pattern. The bags are then cut into perfect squares, and a string and tag are stapled to each bag. Some companies use other materials for tea bags, such as silk or gauze, but they are less common.