What is directory ?
It is a repository of information regarding file structure is directory.
the .git folder contains all the information that is necessary for your project in version control and all the information about commits, remote repository address etc. All are present in this folder. It also contains a log which stores your commit history so that you can roll back to history.
Apache Subversion (often abbreviated SVN, after its command name svn) is a software versioning and revision control system distributed as open source under the Apache License. Software developers use Subversion to maintain current and historical versions of files such as source code, web pages, and documentation.
The purpose of Git is to manage a project, or a set of files, as they change over time. Git stores this information in a data structure called a repository. A git repository contains, among other things, the following: A set of commit objects.
The git init command creates a new Git repository. It can be used to convert an existing, unversioned project to a Git repository or initialize a new, empty repository. Most other Git commands are not available outside of an initialized repository, so this is usually the first command you'll run in a new project.