Herd of workers and supervisors :).In real world workers are doing the actual work and supervisors are monitoring the behaviour of workers
Well ,here it is about Erlang supervisors.In Erlang Workers are processes which perform the actual work whereas supervisors are processes which monitor the behaviour of workers.At the same time supervisor can restart the worker if something goes wrong.
Graphical representation of supervisor and worker.
Rectangular shape -supervisor
eclipse /circular shape -worker.
This is called supervision tree.
According to this supervision tree, there is one supervisor and under that supervisor there is one worker.
In Erlang there are different types of supervisors are defined according to their behavior.