Namecoin

Namecoin
Denominations
Subunit
0.001	mNMC (Milli Namecoin)
0.000001	µNMC (Micro Namecoin)
0.00000001	Swartz
Symbol	ℕ, NMC
Demographics
Date of introduction	18 April 2011; 1st fork of Bitcoin
User(s)	Worldwide
Valuation
Production	21 million Namecoins are released as a geometric series, every 4 years the rate is halved.
Source	Namecoin Statistics
Method	Automatic adjusted difficulty every two weeks.

Namecoin (Symbol: ℕ or NMC) is a and the first fork of the bitcoin software. It is based on the code of bitcoin and uses the same proof-of-work algorithm. It is limited to 21 million coins.

Unlike bitcoin, Namecoin can store data within its own blockchain transaction database. The original proposal for Namecoin called for Namecoin to insert data into bitcoin's blockchain directly. Anticipating scaling difficulties with this approach, a shared proof-of-work (POW) system was proposed to secure new cryptocurrencies with different use cases.

Namecoin's flagship use case is the censorship-resistant top level domain .bit, which is functionally similar to .com or .net domains but is independent of ICANN, the main governing body for domain names.

A peer-to-peer network similar to bitcoin's handles Namecoin's transactions, balances and issuance through SHA256, proof-of-work scheme (they are issued when a small enough hash value is found, at which point a block is created; the process of finding these hashes and creating blocks is called mining). The issuing rate forms a geometric series, and the rate halves every 210,000 blocks, roughly every four years, reaching a final total of 21 million NMC.

Namecoins are currently traded primarily for USD and other cryptocurrencies, mostly on online exchanges. To avoid the danger of chargebacks, reversible transactions, such as those with credit cards or Paypal, are not advised since Namecoin transactions are irreversible.

...
Wikipedia