Marketplaces
Facebook was created to connect with friends, family and individuals across the world. It has grown from just chatting to people, to providing other features such as their marketplace and live streaming services, by using their own (built from the ground up) open-source software. The site is written in php programming language and uses a MySQL database infrastructure. Facebook is one of the largest users of MySQL as well as Memcached, an open-source caching system.