LEGO introduced its first plastic automatic-binding bricks in 1949.
These early bricks were called Automatic Binding Bricks and were based on an earlier interlocking brick design made by the British company Kiddicraft. They were hollow underneath and used studs on top so that bricks could connect and be separated repeatedly.
The bricks were not yet identical to the modern LEGO brick. The design was refined during the 1950s, especially through the addition of internal tubes that improved clutch power and made connections more stable. In 1958, LEGO patented the basic modern brick design.
People sometimes identify 1958 as the beginning of LEGO bricks, but that year refers to the key modern stud-and-tube design. Plastic LEGO construction bricks had already entered production in 1949, several years earlier, alongside the company’s wooden toys.