Renewable energy refers to energy sources that are replenished naturally and can be used indefinitely, unlike fossil fuels which are finite resources. Some examples of renewable energy sources include:

1. Solar energy: Energy from the sun, which can be harnessed using solar panels to generate electricity or heat.
2. Wind energy: Energy generated by wind turbines, which convert the kinetic energy of the wind into electricity.
3. Hydroelectric energy: Energy generated by the movement of water, typically through a hydroelectric dam.
4. Biomass energy: Energy generated from organic materials, such as wood, crops, and waste.
5. Geothermal energy: Energy generated from the heat of the earth, which can be harnessed to generate electricity or heat.
6. Tidal energy: Energy generated from the movement of tides.

These renewable energy sources have several advantages over fossil fuels. They emit minimal or no greenhouse gases, they have low operating costs, and they are sustainable. The increasing concerns about the environmental impact of fossil fuels and the need to reduce carbon emissions have led to a greater focus on renewable energy in recent years. Many countries have set ambitious targets for increasing their use of renewable energy to reduce their dependence on fossil fuels and to combat climate change.