Dialog manager
A dialog manager (DM) is a component of a dialog system (DS), responsible for the state and flow of the conversation. Usually:
There are many different DMs that fulfill very different roles. There can even be several DM components in a single DS.
The only thing common to all DMs is that they are stateful, in contrast to other parts of the DS (such as the NLU and NLG components), which are just stateless functions. The DM roles can roughly be divided into these groups: