system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do most shows call their first episode "Pilot"?
gpt
Pilot come from the the greek word for a oar, rudder you steer  a boat with.  It was transferred to the persons that steer a boat and to a person that know a harbor etc and today it might be as maritime pilot, harbor pilot.

So a pilot is another word for a guide in some context. You for example drill a small pilot hole to guide a nail or a larger drill, the the pilot hole is the first hole you make

So from that is transfer to usage a  a test or a trail  as a pilot study  or initial production as pilot run.  So it is from this use you should look at a pilot episode of a tv show as a test episode that you produce before you commit to produce any more episodes. 

There is a lot of tv pilots that is produced as a test and then it is determine that something have to change or that  it was not a good idea and there is never a series produced. They are usually not made public but some  can found online. Look for unaired pilot or original pilot and you might find som of a show you know, There can be small or large changes and it is not uncommon that some actors are replaced.

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