Solar energy is a source of power that uses energy from the sun. It is a renewable energy source that has been used in many traditional technologies for centuries. It is also in widespread use where other power supplies are absent, such as in remote locations and in space. The primary forms of solar energy are heat and light. Secondary forms and effects include photosynthesis, wind, the Gulf Stream, the hydrologic cycle, fossil fuels and electricity. This section is focused on applications and technology involved in solar energy.