Hydraulics is the science and technology of moving things using liquid pressure, usually with water or oil. The word comes from Greek roots meaning “water” and “pipe.”

Think about pushing down on a bicycle pump: your force on one end creates pressure that moves through the liquid to push powerfully somewhere else. Hydraulic systems work the same way. When a construction worker operates a bulldozer's giant shovel, hydraulic fluid inside steel tubes transfers the force from small levers in the cab to enormous pistons that lift tons of dirt. Car brakes use hydraulics too: when you press the brake pedal, hydraulic fluid carries that pressure through tubes to squeeze brake pads against the wheels.

Hydraulic systems are remarkably powerful because liquids can't be compressed or squished down the way air can. This makes them perfect for heavy lifting and precise control. Dentist chairs, aircraft landing gear, and even theme park rides rely on hydraulics to move smoothly and safely.

Today, hydraulic technology powers everything from car lifts in repair shops to the massive robotic arms that help build skyscrapers. Any time you see machinery doing powerful, controlled work with smooth movements, hydraulics are probably involved.