task-1, task-2, task-3, task-4, … Everyone who working in front end web page development will have some trivals repeating and repeating. Imagine that you are creating a web page from scratch, you need to design the all the pages arrage the relationships between different pages and other websides. Then you need to implement every single pages. You should figure out the common part and reusable part and put them together, and use some client-side or server-side mothods to merge all different part together and represent a perfectly metched web page to your audience. If you achieve the goal via a client side method such as frameset of iframe tag in web page, then you can hardly prevent user directly visit a fragment of a layer of your final site. In some other scrnarios, some one directly use the same method as you do to put your site fragment into their web pages. Isn’t it annoying?