The Tesco Clubcard logo. (Photo credit: Wikipedia)
For Facebook they mostly use PHP compiled into C++
PHP is a server-side scripting language designed for web development but also used as a general-purpose programming language.
C++ (pronounced “see plus plus”) is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language.
- Facebook uses Linux, but has optimized it for its own purposes (especially in terms of network throughput).
- Facebook uses MySQL, but primarily as a key-value persistent storage, moving joins and logic onto the web servers since optimizations are easier to perform there (on the “other side” of the Memcached layer).
Tesco uses Clubcard to “reward” their customers.
http://www.tesco.com/clubcard/clubcard/About – Clubcard – Tesco.comwhat.asp
websites such as Facebook, twitter and Skype are used as social sites. On Skype you can video call