.git directory is a hidden folder automatically created by Git in the root of a repository. It contains all the information required for version control, including the complete history of changes, configuration settings, and references to branches and tags. This directory allows developers to track modifications, revert to previous states, and collaborate efficiently. Exposing the .git directory on public servers is a serious security risk, as attackers could access sensitive code, commit history, or credentials. Proper server configuration should always prevent external access to this directory to protect the integrity and confidentiality of the project.