What does git init do and what is inside the .git folder?

git init turns a folder into a Git repository by creating a hidden .git directory. That folder holds the entire history and configuration; the files you edit are only the working tree on top of it. Delete .git and the project stops being a repository.

Main contents:

• HEAD: a file that says which branch or commit is checked out.
• objects/: the database of blobs, trees, commits and tags.
• refs/: branches, tags and remote-tracking branches, each a file holding a hash.
• index: the staging area.
• config: repository-level settings such as remotes.
• hooks/: sample scripts that run on events like commit.
• info/exclude: personal ignore rules that are not shared.

git init -b main
ls .git
cat .git/HEAD    # ref: refs/heads/main

-b main sets the initial branch name. Cloning a repo also creates this folder and copies the full history into it.

Never edit files in .git by hand unless you know exactly why; use Git commands.