The code behind Bitcoin is open source. Not only does this enable investigation of the inner workings of the software, but also the ability to develop other programs from it. The list of alternative cryptocurrencies (called altcoins) is huge. At this time, there are at least 200 coins that exist outside of Bitcoin  and more being released just about every day. Some are meant to complement Bitcoin, while others try to compete by addressing deficiencies with the Bitcoin system. A few are being developed simply to be trophies, deriving value from their extreme rarity. Some are attracted to them because they are easier to mine than mining bitcoin. While the list is extensive, here are a few that are out there:
Litecoin – It’s said that if Bitcoin were gold, Litecoin would be silver. The most used altcoin, it was developed to allow mining with consumer grade equipment, like video cards. It does this by using a different algorithm for mining, called Scrypt. Transaction confirmations are faster with Litecoin than Bitcoin, at around 6.5 minutes per block.
Peercoin – One of the problems with Bitcoin is the “51% Attack” in which an entity controls more than half the mining power of the network, effectively gaining control of it. Peercoin addresses this by using a system that would require an attacker to instead control 51% of the peercoins in circulation, which would be far more expensive than controlling the mining power and would leave the attacker in the position of not wanting to destroy the wealth they accumulated. Because it doesn’t rely on a powerful network to be secure, it requires far less electricity than Bitcoin.
Namecoin – A centralized Domain Name System, currently through ICANN, runs the risk of censorship and outages. Namecoin was designed to counter that. While it can be used as a currency, its purpose is to serve as a decentralized DNS. It uses the .bit domain. A bonus with Namecoin is that it’s able to be merge mined with Bitcoin, meaning you can mine both with the same equipment at the same rate that you could mine either by itself.
Primecoin – Another complaint about Bitcoin is that the mining, while essential to the network, uses so much electricity and computing power only to process payments. Primecoin addresses this by make the mining useful, by finding prime numbers. Prime numbers are very useful for scientists and mathematicians, so much so that the EFF has monetary rewards for finding primes of certain sizes. Similar to Primecoin is Riecoin which also uses mining to find prime numbers.
Devcoin – A coin that is meant to support open source projects. Developers and writers can earn devcoins by writing code or articles. Or people can earn devcoins through bounties, which are tasks others want to see come to fruition and are willing to pay for with devcoins. These bounties are based on market capitalization and apparently one of the ultimate goals for Devcoin is to reach a market cap that allows a bounty to be offered for an open source space craft that can go to space and then return. Like Namecoin, it can also be simultaneously mined with Bitcoin miners.
Dogecoin – Named after the Doge internet meme featuring the Shiba Inu, Dogecoin was launched in December 2013. While many coins developed have a technical purpose – whether it’s addressing a shortcoming of other coins or simply fulfilling another need – Dogecoin was developed simply to be Bitcoin but with more appeal. The name was something everyone on the internet could relate to. And it wouldn’t have the negative connotations associated with it like bitcoins did with the underground marketplace Silk Road. As a testament to the value of cryptocurrencies, the Jamaican bobsled team raised $25,000 to help fund their trip to the 2014 Winter Olympics. It’s also made to have a lot more coins that Bitcoin. After the first year alone of Dogecoin’s existence, there will be 100 billion dogecoins in circulation. Wow.
Mastercoin – A new protocol as opposed to a new coin, it was developed to work with Bitcoin. Mastercoin enables trading Smart Property and Smart Contracts. Its aim is to take Bitcoin to the next level, facilitating the trade of higher value property.
Takeicoin – Following the trend of naming coins after internet memes and celebrities, Takeicoin was named after actor George Takei. Like its namesake, it was developed with human rights causes in mind. The creators of the coin are very active themselves in various political and social issues and wanted to make it easier for non profits and charitable causes to be able to receive funding quickly and easily.