Kadomtsev–Petviashvili hierarchies of types B and C

This is a short review of the Kadomtsev–Petviashvili hierarchies types $$\mathrm{B}$$ and $$\mathrm{C}$$ . The main objects are $$L$$ operator, wave auxiliary linear problems for function, bilinear identity tau function. All them discussed in paper. Connections with usual (type- $$\mathrm{A}$$ ) hierarchy clarified. Examples soliton solutions dispersionless limit also considered.