The Generalized Nets (GNs) are extensions of Petri nets and of different Petri nets modifications, introduced by the author (1982). In the book, definitions and the basic properties of GNs are given. The GNs extensions and reductions are discussed. GNs, which describe the functioning and results of the work of different types of petri nets, different types of finite automata and of Turing machines, are given. Over the GNs are defined different operations, relations and operators. They can also be transferred onto other nets. Many open problems in the GNs theory are given.