the history of programming( the development of facebook )

As the social media circuit grows software advances throughout each site. With these sites increasing in popularity attention grows and the integration of marketing and advertisement makes the social media industry a multi billion dollar industry. But what is the code written in these sites that makes it so popular. PHP is used for the development of facebook it is basically a scripting language used for web design and also general purpose programming.
http://www.warriorforum.com/programming-talk/497316-what-programming-language-facebook-written.htmll

From the above link the reader will be able that zuckerberg initially used the likes of PHP , Apache unix but later incorporated C++ techniques that was used for front end development.

But why was facebooks engineers stuck with languages like PHP ?

http://www.zdnet.com/blog/facebook/why-facebook-hasnt-ditched-php/9536

from the above link the reader was able to see the main reason why facebook hasn't strayed away from PHP is that its engineers have managed to solve all flaws associated with this software. It is evident from reading this link that facebook has sort of in a way created a language with in its self for the use of facebook only by incorporating other techniques used in java ,orcale and C++ . The below caption shows some of the early source code written in PHP to develop facebook