So, what is Nuclear Energy?
In layman's terms...
...Nuclear Energy is the creation of electrical energy and power from the splitting of heavy atoms (nuclei) in a process called nuclear fusion. Usually, it is done with atoms of elements like uranium, plutonium, and possibly thorium.
Like other power plants...
...nuclear power plants heat water and turn it into pressurized steam to turn a turbine. Power plants like coal, oil, natural gas, and geothermal. Fun fact: cooling towers, like the one on the top of this page, are not unique to nuclear power plants.
Unlike other power plants...
...nuclear is one of the most reliable with a plant operating at full capacity 90% of the time. In fact, they only need refueling every couple of years. They also need a relatively small area to produce power: 1.3 square miles per every 1,000 megawatts of power generated
Additional Information.
In the U.S. there are 92 nuclear reactors all held within 54 nuclear power plants spread across 28 states. They produce about half the carbon-free electricity in the country. Speaking of which 19% of the U.S.'s power comes from Nuclear.
Nuclear compared to other power sources is very dense in its energy production to fuel mass. Take one ton of coal, or 120 gallons of oil, or 17,000 cubic meters of natural gas. The amount of nuclear fuel used would be the size of a decent-sized pebble. To take it further you would need 1.1 kg or 2.4 pounds of fuel to supply all your electrical needs for a lifetime.