在鐵人賽開始之前，已經先上玩這個課程裡面的 JavaScript、CSS、HTML，接著已經完成了三個網頁的小遊戲，其中一個小遊戲是 The Simon Game，就是鐵人賽開始的第一到三天在做的事。

現在課程到需要了解一些 Backend Web Development 的階段，先記一下今天上課抄下的 command line 有哪些：

-  ls => List ( All things in the file, and use it to check where you are)
-  ~  => Root
-  cd => Change Directory
   cd ~ => Root Directory
   cd .. => Back to the previous level
-  'option' : go anywhere with cursor/keyboard
-  'control' + 'U' : clear the command line

-  mkdir => make a directory (a folder)
-  touch => create a new file
   : touch Text2.txt
-  open => open a file
   : open Text2.txt
   : open -a Atom Text2.txt => open .txt file with Atom
- rm => remove file
   : rm Text.rtf
   : rm  * => delete all the file
   : rm -r Document/ => delete the directory
- pwd => print working directory

以及課程用「開餐廳」來簡單地說明了前端、後端都在做什麼：

Frontend : HTML, JavaScript, CSS
Backend : Server, Application, Database

let's say if you are running a restaurant...
- client-side: Restaurant 
- Server : Kitchen
- Database : Larder