Read the documentation and you get one story, go on a training course and you get another

/etc is the nerve center of your system, it contains all system related configuration files in here or in its sub-directories

Linux Filesystem Hierarchy

Actually, the truth is a little less planned.

It transpires that the original creators of Unix – Thompson and Ritchie (who went on to develop the C programming language, to migrate their Unix Operating System) – tried to organise their files into a proper structure. /bin for binary files, /sbin for system binaries, and so on.

But what did they do with everything they couldn’t find a place for.

They stuck it in /etc

etcetera by name and etcetera by nature.