Namecoin is a cryptocurrency with a decentralized peer-to-peer key/value data storage system. It is an alternative Domain Name System and makes Internet censorship more difficult as it builds a decentralised DNS outside of ICANN control.
Namecoin currently uses the .bit domain and these domains can be purchased using namecoins. To resolve the .bit domains you need either the current block chain or use a public name server that participates in the Namecoin system.
Namecoin is a Bitcoin fork and has a limit of 21 million Namecoins. It uses the SHA-256 algorithm. Namecoin was launched on 18 April 2011 and in September 2011 Namecoin was switched to merged mining with Bitcoin.