Which is the most used on Facebook?

Answer 1

it's here ↓↓↓ :)
https://www.quora.com/What-programming-languages-are-used-at-Facebook-Where-is-each-one-used

Answer 2

Web front-end written in PHP. Facebook's HipHop
Compiler then converts it to C++ and compiles it
using g++, thus providing a high performance
templating and Web logic execution layer.

Answer 3

hmm

Answer 4

phyton and ruby

Answer 5

THE LANGUAGES WHICH ARE USED FOR @FACEBOOK
are given below.....

front-end. back-end. database

JavaScript. PHP. my SQL
XHP. HBase
JAVA
C++
PYTHON