Include <library> vs "library"

I have to admit that this is all going over my head at my current level of understanding.

I have however managed to dig out an old post which has helped me achieve what I wanted to do. The post is help using the time library on ESP32

I can find the constituent parts of the time with

timeinfo.tm_sec

etc.

For a beginner, the most useful part of a library is a really good Readme file in the library folder. I can’t find one though for the time.h folder.

Thanks for every bodies help.