In the world there are many types of energy sources, but I think wind energy is the most popular. It is a renewable energy source, so it has many advantages. Firstly, it is not harmful to the environment, people will not need to worry about environmental problems when using it. Second, wind energy lasts forever, and like tidal or solar energy, we will never run out of it. Third, it is cost effective. There are no costs associated with buying or transporting fuel into wind turbines, like coal-fired power plants. In addition, with advancements in technology, wind energy will become cheaper, thereby reducing the amount of capital that countries have to spend to meet their energy needs. However, it also has disadvantages. Windmills will make noise for everyone nearby, causing noise pollution. Not only that, the animals around it can also be in danger. Are birds safe to crash into windmill wings? Despite the downsides, the advantages of wind power are also great. It would be great if we humans use it in the future.