Namecoin

Namecoin is a cryptocurrency that was introduced on April 18, 2011 that acts as a decentralized domain registry service and domain name system. Namecoin was the first fork of Bitcoin, and shares many properties associated with Bitcoin. The blockchain infrastructure of Namecoin allows its domain name registry service to be censorship resistant and unaffected by activity tracking issues associated with non-blockchain based domain registry services.

Just like Bitcoin, Namecoin uses the same source code, proof-of-work protocols, and is also limited to 21 million coins. Where Namecoin differs from Bitcoin is in its ability to store data on its own blockchain transaction database that is capable of storing data. Namecoin is used to register .bit domain names and store associated values on the Namecoin blockchain. Values stored by Namecoin are limited to 520 bytes and have a block size limit of between 50 kB and 1 MB.

The Namecoin domain registry service adds another layer of human readable information on-top of the Bitcoin source code called NameID. NameID is Namecoin's method of solving the problem of Zooko's triangle associated with Bitcoin, which provides security and decentralization but is not human readable.