What is Formation and dissociation constants?

For a central ion M and a ligand L (charges omitted), the overall formation constant of $\mathrm{ML}_n$ is the constant $\beta_n$ of $\mathrm{M} + n\,\mathrm{L} \rightleftharpoons \mathrm{ML}_n$,

The successive formation constant $K_i$ is that of the addition of one ligand, $\mathrm{ML}_{i-1} + \mathrm{L} \rightleftharpoons \mathrm{ML}_i$. The dissociation constant is the inverse, $K_d = 1/K_i$, and $\mathrm{p}K_d = \log K_i$, so that a complex/ligand pair is described exactly like an acid–base pair, with the ligand in place of the proton.