See the git-config(1) man page, or run git help config
for general information on how Git configuration is arranged.
The [core]
section refers to things that control the “core” of Git’s behavior: how files & updates are recognized, caching, compression, etc., etc.
The defaults are usually—just about always—what you want, but since many people do want to customize the *crlf
options, they have been made explicit and put in a place convenient for changing.