Git 流程

名詞：
Working Directory(Working Tree、workspace)
Index(Staging Area、Staged files、Directory cache)
local repository
remote repository

流程：

<-------------------------- client -----------------------------> <--- git server -->
 Working Directory  |  Index(Staging Area)  |  local repository  |  remote repository
         (add)--------------->
                           (commit)---------------->
                                                (push)------------------->
                                                
            <---------------------------------(merge) <-------(fetch)-----
                   merge origin/master into master     update origin/master
                         
            <------------------------------------------------(pull)------
            
            <-----------(checkout revision)---------