Popular Internet applications

Why did we choose the Internet applications in this book and not others? Firstly and most obviously, the applications must be popular and have a large number of users. Secondly the application should be a mainstream one for consumers and not for businesses. We want applications that have a more direct interface to the final consumers of the application. Thirdly, we don't want to deal with payment related issues in this book so any e-commerce applications are left alone. The reason is simple—e-commerce is no longer rocket science but implementing payment well is still not a trivial undertaking, and we did not want to mislead users into believing it is easy to clone payment features. Finally (and most importantly for me) the applications we chose to clone must also be easy to implement and would fit in nicely into a single chapter.

With these criteria, we have picked the following small number of applications to cover in this book:

• A URL shortener—TinyURL
• A microblogging application—Twitter
• A photo sharing application—Flickr
• A social networking service—Facebook

It's interesting that none of the crop of popular Internet applications we are cloning in this book is the true original implementation of the main idea in that application. There have been URL shorteners before TinyURL, there were micro-blogging sites before Twitter, photo-sharing before Flickr, and definitely social networking services before Facebook. However, each of these is, as of writing, the most popular service of its kind.