Pseudostates can be of different kinds: initial, deep history, shallow history, join, fork, junction, choice, entry point, exit point, terminate or reference.
Initial
An initial pseudostate represents a default vertex that is the source for a single transition to the default state of a composite state.
Deep History
deepHistory represents the most recent active configuration of the composite state that directly contains this pseudostate (e.g., the state configuration that was active when the composite state was last exited).
Shallow History
Shallow history represents the most recent active substate of its containing state (but not the substates of that substate).
Fork
Forks serve to split an incoming transition into two or more parallel transitions.
Join
Join serves to merge several transitions into only one transition.
Choice
A choice splits transitions into multiple outgoing paths.
Junction
Junctions are used to construct compound transition paths between states.
Entry point
An entry point pseudostate is an entry point of a state machine or composite state.
Exit point
An exit point pseudostate is an exit point of a state machine or composite state.
Reference
It is a reference to an entry or an exit of a state machine or composite state.
Terminate
Entering a terminate pseudostate implies that the execution of this state machine by means is terminated.