Water is the most important liquid known to mankind. It is found everywhere; on the ground or even in the air we breathe, and is used as an essential part of everyday life. Hundreds of years ago, people used water for irrigation and the operation of various mechanical devices such as water mills. As a result, it leads people from one idea to another until they decide to try using water to generate electricity. This new discovery led to success. To promote this new idea, people began building dams across the country to help them store water so generation could take place. Of course, with the help of the water cycle, the discoverers of hydraulic electricity generators lead to the discovery of one of nature's engines for creating a useful form of energy. As is known to many people of these new generations, electricity can be reproduced in many ways, with the help of natural resources, wind energy, the solar system and fossil fuels. One that is actually used by numerous countries is hydroelectric power. Hydroelectric power or water power is the energy derived from the energy of falling water and flowing water that could be harnessed for useful purposes. There are three main methods for generating hydroelectric power. First, storage, where a dam collects water in a reservoir and then releases it to drive turbines, producing electricity. Second, pumped storage, where water is pumped into a higher tank and released into a lower tank. Third, river flow, known as the most popular method, in which the natural flow of a river or stream is used to drive a turbine. As mentioned above, water supply is used by many people to accomplish many aspects on a regular basis. Looking back, thousands of years ago, the Greeks would have represented f... half of paper... power plants produce fewer greenhouse gas emissions than other power plants. On the other hand, the construction of a dam affects the ecosystem of the river and the surrounding area. Therefore, some fish species cannot increase their population because of them. Although hydroelectric dams produce considerably fewer emissions than thermal power plants, the water trapped in the dam causes methane to be released into the atmosphere. The use of water is infinite. A new idea led to other ideas until some engineers invented using water to generate electricity. Even though it was discovered and used thousands of years ago for simpler things, the idea has been expanded by some people and used in a way that could help both people and the environment. Now dams are being built everywhere because it is known as one of the best ideas for generating electricity.