That of the domain which serves the synchronization and communication of cooperating sequences of activities.

Something that can be done to one or more entities, e.g. opening an account for a person.

That of the domain which will, in a software design, best be represented by (global or member) functions.

A type of "thing" in the domain that usually has attributes.

An instance in time when an action starts or ends, e.g. the movie-goer has just decided on the movie to watch.

That of the domain which will, in a software design, best be represented by instances of classes.

A sequence of several events and actions (possibly seen together with another such sequence of events and actions).

That of the domain which will, in a software design, best be represented by threads or processes.