which did language is used to make quora application

For developing Quora, the codes are mostly written in Python and JavaScript programming languages.
Pylons' framework is used as a starting point for the development but about half of it has been replaced by their own custom systems known as LiveNode / webnode2. The part of the infrastructure which is written using JavaScript, is built on top of jQuery. 
Thrift is used to communicate between different the various backend systems.
The main webserver is paste with nginx and HAProxy in front of it.
For Comet server, Tornado is used.
For hosting purpose, Amazon EC2 and S3 find their uses.
The database is created using MySQL and its management is also done using the same.