The word anecdote came from the Greek word Anekdota which means a collection of unpublished short tales of biographical incidents or memoirs.
An anecdote is a short tale based on real life event. It is a brief narrative of a notable, amusing, inspiring, or interesting biographical incident involving a real person, famous or not. An anecdote highlights a human character trait or reveals a personal interaction without attempting to convey a moral lesson as those found in fables and parables.
Unlike a short story that may have a complicated plot involving a series of events, an anecdote refers to a single uncomplicated event, or episode, that is unified in space and time.
Anecdotes are sometimes humorous but they are not to be confused with jokes. Humorous anecdotes are based on notable personal experiences that reveal a true human character and behaviour in a particular incident, and, as such, they seek to inspire others in a humorous way.
On the other hand, jokes are also humorous short tales but their primary intent is to entertain and evoke laughter, not to inspire. Their story lines are sometimes exaggerated, or untrue, to create a more effective punch line.
A sub-category of jokes are monologues which are made famous by late night television shows. A monologue usually include several unrelated incidents, and is sometimes used to convey a ridicule, critique, or political message in a humorous way.
Because anecdotes are based on actual events involving real persons, some anecdotes are used to validate or reinforce certain pronouncements or claims such as those relating to the promotion of certain products or services. Those narrations are sometimes to as anecdotal evidence but those should be more appropriately called testimonials.
Anecdotal evidence maybe useful in selling a product, or service, but they have very little value in the scientific and legal community because the narrative is not subjected to scientific or judicial review.
Fables are also short tales that are notable, amusing, inspiring, and interesting but, unlike anecdotes, fables are ancient fictional stories that revolve around animals as principal characters. The main intent of the stories is to convey a moral lesson and, in the process, to influence human behaviour.
Parables are partly similar to anecdotes and fables but they are different in that they contain both real and fictional events, and the narration is given in some historical perspective. Parables usually use metaphor to convey a moral or spiritual message to influence human behaviour.
In summary, an anecdote is:
a short true biographical tale
of a single incident unified in space and time
that is notable, interesting, amusing, or inspiring
involving a real person and place
to delineate, or reveal, a human character or interaction