If the solar spectrum is closely examined, it is found that it consists of large number of dark lines. These dark lines in the solar spectrum are called Fraunhofer lines.Solar spectrum is an example of line absorption spectrum.
The central core of the sun is called photosphere which is at a very high temperature of the order of 14 million kelvin. It emits continuous spectrum. The sun's outer layers called chromosphere. this is at a comparatively lower temperature at about 6000 k. It contains various elements in gaseous state.
When light from the central core of the sun passes through sun's atmosphere ,certain wavelengths are absorbed by the elements present in the chromosphere and the spectrum is marked by dark lines.
By comparing the obsorption spectra of various substance with the Fraunhofer lines in the solar spectrum, the elements present in the sun's atmosphere have been identified.