Git hooks are executable scripts you can place in $GIT_DIR/hooks directory to trigger action at certain points.

To install manually, run:

  cd .git/hooks && ln -s ../../.git-hooks/* ./
  
When you using GIT for Windows, you need Windows links
Open a Dos-Box with admin rights then
  cd .git/hooks
  FOR /F " usebackq " %i IN (`dir /b ..\..\.git-hooks`) DO mklink %i ..\..\.git-hooks\%i

There are two groups of these hooks: client side and server side.

The client-side hooks:
are for client operations such as committing and merging.

The server-side hooks:
are for Git server operations such as receiving pushed commits.

See Also [ http://git-scm.com/book/en/Customizing-Git-Git-Hooks ]