system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What exactly are the Freemasons?

I've seen a few cars lately sporting a Freemason decal. I basically am just curious to know everything about it. 

ninja edit: I've tried reading Wikipedia to try to understand it but there is just too much information to handle.
gpt
Freemasons are members a of social club.  They gather once or twice a month and hang out.  Outside the meeting hall, Freemason try to improve society and themselves.  They do so by volunteering or doing other charitable acts.  Freemasons consider one another as brothers, and like real brothers, they will help eachother out.

There is a secretive element to the Freemasons.  They have a lot of historical knowledge and rituals that they do not reveal to the public.  The secrets are not world changing.  A Freemason did an AMA once, and he said that the secrets of Freemasonry are similar to the secrets of a good book or movie.  They stay quiet because they do not want to ruin to story for others.

EDIT: Freemasonry is open to most people: you must be a man, must be older than 21 (that might vary in different regions), must be born a free man, and must believe in a higher power.  If you ask a Freemason to join, it is their duty to help you do so.