Namecoin

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Namecoin is a cryptocurrency that started as a fork of Bitcoin. It shares Bitcoin’s proof-of-work security and has a total supply limited to 21 million coins. It uses merged mining, so miners can secure Namecoin and Bitcoin at the same time, and it creates new blocks about every 10 minutes.

Beyond money, Namecoin can store data in its own blockchain. Its main idea is to support a decentralized name system, most famously the .bit top-level domain. .bit is similar to .com or .net but runs independently of ICANN. In practice, only a few .bit sites are active, and OpenNIC stopped supporting .bit in 2019 due to security and malware concerns.

How records work: each Namecoin record has a name and a value. Names are structured as paths, like d/example, where the namespace precedes the name. To register a record, a small fee of 0.01 NMC is charged, and records expire after about 36000 blocks (roughly 200 days) unless renewed.

In 2013, Namecoin launched NameID, which lets people associate identities with Namecoin and provides an OpenID-style login option for websites, including a password-less authentication method. Namecoin also activated merged mining with Bitcoin on block 19200, letting miners secure both networks without choosing one over the other.

A security issue in 2013 briefly exposed a way to modify foreign names, but it was fixed quickly and reportedly never exploited, except as a proof-of-concept on bitcoin.bit. Namecoin has been mentioned as an example of distributing DNS control and privacy, but a 2015 study found that most Namecoin names were not in use (only 28 of about 120,000 names).

As of early 2021, Namecoin remains active. It’s developed as a separate project from Bitcoin, with ongoing releases (the latest listed here was 0.21.0 in January 2021). The project has a history of exploring uses like notary and timestamp systems in addition to domain names.