Which Lego theme features gears, axles, and mechanical parts?

Which Lego theme features gears, axles, and mechanical parts? Lego Technic is the answer.

Introduced in 1977 as Expert Builder or Technical Sets, the line was renamed Lego Technic in 1982. Unlike ordinary Lego System sets, Technic models use beams with holes, pins, axles, gears, joints, and specialized connectors to create working mechanisms. Builders can make steering systems, gearboxes, suspension, cranes, engines, and other functional machines.

Gears have been part of Technic since its launch, transferring rotary power and changing speed or torque. Pneumatic components appeared in Technic products in 1984, while motorized systems later enabled remote-controlled and app-controlled models. Since about 2000, many sets have used studless construction, relying heavily on beams and pins rather than traditional studded bricks.

A common mix-up is Expert Builder: that was an earlier name for the same general line, not a separate modern theme. Lego Creator can also include moving models, but Technic is the theme specifically associated with mechanical engineering-style construction.