It is pointed out that the phenomenon of solar rotation is known since the introduction of the telescope into astronomy by Galilei in 1610. Regular measurements concerning the positions of sunspots were conducted with the aid of photographic plates at the Royal Greenwich Observatory during the time from 1874 to 1976. The obtained data provide an excellent basis for statistical analysis. Information obtained as a result of such analyses is discussed. Attention is given to the determination of the Wilson depression, details regarding solar differential rotation, plans for an evaluation of data with the aid of a computer, the rotation of the solar plasma, a comparison of sunspots and plasma, the theory of differential rotation, and new information concerning solar rotation partly obtained with the aid of solar telescopes in a Spanish observatory on the island of Tenerife.