Here are the web technologies used to build the most famous and largest web sites in the world, you can click on the links if you want to see references or more details.
Facbook.com
written in PHP, C++ and Java
data is output in PHP format (compiled with HipHop for PHP). The backend is written in Java and Thrift is used as the messaging format so PHP programs can query Java services.here
HipHop converts PHP into heavily optimized C++ code, which can then be compiled into an efficient native binary. the company's engineers reported that it reduced average CPU consumption on Facebook by roughly 50 percent. here
eBay.com
from Perl .. to .. XSL(front end) & C++ (back end) .. to .. XSL (front end) & Java (back end)
Youtube.com
written in Python
Twitter.com
from Ruby on Rails .. to .. Scala .. to .. Java
James Gosling explaining why twitter moved from ruby to java
Amazon.com
written in C++ and Java with Oracle database engines on Linux-based Hewlett Packard servers
LinkedIn.com
written in Java
PayPal.com
written in C++
