why mark zuckerberg used c++ and java while making facebook even after using javascript,php,sql ?

[Neerp]

c++ is used when you want performance. It is extremely fast. It is also the most difficult to use in that you need a good education and background in various computer science topics to be proficient in c++.

Java is for those not smart or educated enough to use c++, or too lazy to manage their own garbage collection. It is slow and bloated, and causes a lot of problems if the right jvm is not present. Write once run anywhere doesn't quite work like they would have you believe because the next thing you know java is updated or internet explorer is updated and your java apps don't run.

PHP is not a scripting language, it is a programming language that is moderately fast and quite capable. Unlike java that has to be downloaded to your computer and run on your computer, PHP runs on the web server, and it is only the results that get sent to your browser. Many websites are written in PHP. With PHP you usually use javascript as well as html/css. On the back end you would use a database, and mysql is quite popular.

Python I've not used much for the simple reason that I've never needed it. It's a handy scripting language, but between c++ and PHP, I've never needed Python.

Yes, you can make a full blown website using PHP. I do exactly that for a living, and it works very well.