This chapter gives a general introduction to the subject matter. It proceeds from explaining the five main aspects of solar forecasting, namely, base forecasting methods, post-processing, irradiance-to-power conversion, verification, and grid integration. Particularly important is the last aspect, which has been ubiquitously used as the motivation for making solar forecasts, however, how exactly such forecasts can benefit the power grid operations are often ambiguous. In this regard, three applications of solar forecasts are detailed; they are: regulation and load following, power system stability and control, and transmission and distribution planning. These applications must be understood in great depth, such that the solar forecasts generated can be of use to system operators.