The extension of the Bloch equations regarding chemical exchange are shown and analyzed. Analytical solutions provide sound insight in the Bloch-McConnell equation system that underlie every exchange-weighted contrast, be it CEST, T1ρ or T2, as well as semisolid magnetization transfer. In this lecture we show that for all experiment affecting the water magnetization, a single eigenvalue solution is able to describe all these experiments. This knowledge forms the basis for interpretation of the outcomes of different exchange-weighted contrasts as well as quantification of exchange.