The fractional domatic number of a graph G is the maximum ratio \(|\mathcal {F}|/m(\mathcal {F})\) over all families \(\mathcal {F}\) of dominating sets of G, where \(m(\mathcal {F})\) denotes the maximum number of times any particular vertex appears in \(\mathcal {F}\). The fractional idiomatic and fractional total domatic numbers are defined analogously with all families \(\mathcal {F}\) of independent dominating sets and total dominating sets of G, respectively. In this chapter, we survey some results on the three parameters and their relationship with and extension to hypergraphs.