An assembly line is a manufacturing system where a product moves past a series of workers or machines, each performing one specific task, until the finished item emerges at the end. Imagine building a LEGO spaceship where one person only attaches wings, the next adds engines, the next installs the cockpit, and so on, with the spaceship sliding down a table from station to station.

Henry Ford pioneered the moving assembly line in 1913 to build Model T automobiles. Before assembly lines, skilled workers built entire cars from start to finish, which took a long time and made cars expensive. Ford's assembly line slashed the time to build a car from over 12 hours to about 90 minutes. Each worker mastered one simple task and repeated it hundreds of times per day. This made cars affordable for ordinary families and transformed American life.

The assembly line method spread beyond cars to nearly every kind of manufacturing: toys, computers, furniture, and countless other products. The approach dramatically increased production speed and lowered costs, though some criticized it for making work repetitive and boring. Today's assembly lines often use robots for dangerous or tedious tasks, with human workers handling more complex operations.

The term also gets used metaphorically. Teachers might joke about avoiding an “assembly line approach” to education, meaning they want to treat each student as an individual rather than pushing everyone through identical steps.