Tidal energy harnesses the predictable rise and fall of ocean tides caused by gravitational forces from the moon and sun. It can be generated using two methods: tidal range uses barrages and lagoons to capture potential energy from changing tide levels, while tidal stream extracts kinetic energy from tidal currents using structures like tidal turbines. Tidal energy is a renewable source and more predictable than wind and solar, but development has been limited by high costs and few locations with sufficiently high tidal ranges or currents. New technologies aim to overcome challenges and make tidal power more economically and environmentally viable.