As a typical star, and the only one that can be spatially resolved by direct means, the study of the Sun has provided an insight into many of the fundamental processes taking place in stellar atmospheres, often at small scales. A prime example is magneto-convection or the formation of coronae and the consequent emission of copious amounts of X-rays. In addition, the Sun’s apparent brightness allows measurements with unprecedented accuracy. Thus the Sun is the standard against which cosmic abundances are compared. Its high apparent brightness also means that the Sun is a strong source at almost all wavelengths and thus detectable with simple, not particularly sensitive equipment such as the early instruments flown in space. Thus for many wavelengths the Sun was the first (or one of the first) cosmic source(s) detected.