Nearly all other digital currencies are centrally controlled. This means that:

Being decentralized, Bitcoin solves all of these problems.

Unlike gold, bitcoins are:

Unlike fiat currencies, bitcoins are:

Unlike electronic fiat currency systems, bitcoins are:

Bitcoin's properties cannot be illegitimately changed as long as most of bitcoin's economy uses full node wallets. Transactions are irreversible and uncensorable as long as no single coalition of miners has more than 50% hash power and the transactions have an appropriate number of confirmations.

Bitcoin requires certain properties to be enforced for it to be a good form of money, for example:

These rules define bitcoin. A full node is software that verifies the rules of bitcoin. Any transaction which breaks these rules is not a valid bitcoin transaction and would be rejected in the same way that a careful goldsmith rejects fool's gold.

Full node wallets should be used by any intermediate bitcoin user or above and especially bitcoin businesses. Therefore anybody attempting to create bitcoins with invalid properties will find themselves being rejected by any trading partners. Note that lightweight wallets and web wallets do not have the low-trust benefits of full node wallets. Lightweight (SPV) wallets will blindly trust the miners, meaning if 51% of miners printed infinite coins or spent the same coin twice then lightweight wallet users would happily accept these fake bitcoins as payment. Web wallets blindly trust the web server which could display anything at all.

Miners are required to choose between multiple valid transaction histories. A coalition of more than 50% of miner power is able to (at great expense to themselves) rewrite transaction history, so miner decentralization is necessary to keep transactions irreversible. Miners burn a lot of electrical power in the mining process so they must constantly be trading their bitcoin income in order to pay bills. This makes miners utterly dependent on the bitcoin economy at large and therefore gives them a strong incentive to mine valid bitcoin blocks that full nodes will accept as payment.

Influential figures in the community (such as developers, politicians or investors) may try to use their influence to convince people to download and run modified full node software which changes bitcoin's properties in illegitimate ways. This is unlikely to succeed as long as counterarguments can freely spread through the media, internet forums and chatrooms. Many bitcoin users do not follow the bitcoin forums on a regular basis or even speak English. All appeals to run alternative software should be looked at critically for whether the individual agrees with the changes being proposed. Full node software should always be open source so any programmer can examine the changes for themselves. Because of the co-ordination problem, there is usually a strong incentive to stick with the status quo.

See also: Full_node#Economic_strength See also this blog post: Who Controls Bitcoin?

It is not correct to say that Bitcoin is "backed by" processing power. A currency being "backed" means that it is pegged to something else via a central party at a certain exchange rate yet you cannot exchange bitcoins for the computing power that was used to create them. Bitcoin is in this sense not backed by anything. It is a currency in its own right. Just as gold is not backed by anything, the same applies to Bitcoin.

The Bitcoin currency is created via processing power, and the integrity of the block chain is protected by the existence of a network of powerful computing nodes from certain attacks.

One could argue that gold isn't backed by anything either. Bitcoins have properties resulting from the system's design that allows them to be subjectively valued by individuals. This valuation is demonstrated when individuals freely exchange for or with bitcoins. Please refer to the Subjective Theory of Value.

See also: the "Bitcoin is backed by processing power" myth.

This statement is an attempt to apply to Bitcoin the labor theory of value, which is generally accepted as false. Just because something takes X resources to create does not mean that the resulting product will be worth X. It can be worth more, or less, depending on the utility thereof to its users.

In fact the causality is the reverse of that (this applies to the labor theory of value in general). The cost to mine bitcoins is based on how much they are worth. If bitcoins go up in value, more people will mine (because mining is profitable), thus difficulty will go up, thus the cost of mining will go up. The inverse happens if bitcoins go down in value. These effects balance out to cause mining to always cost an amount proportional to the value of bitcoins it produces[1].

This is simply not true. Each bitcoin gives the holder the ability to embed a large number of short in-transaction messages in a globally distributed and timestamped permanent data store, namely the bitcoin blockchain. There is no other similar datastore which is so widely distributed. There is a tradeoff between the exact number of messages and how quickly they can be embedded. But as of December 2013, it's fair to say that one bitcoin allows around 1000 such messages to be embedded, each within about 10 minutes of being sent, since a fee of 0.001 BTC is enough to get transactions confirmed quickly. This message embedding certainly has intrinsic value since it can be used to prove ownership of a document at a certain time, by including a one-way hash of that document in a transaction. Considering that electronic notarization services charge something like $10/document, this would give an intrinsic value of around $10,000 per bitcoin.

While some other tangible commodities do have intrinsic value, that value is generally much less than its trading price. Consider for example that gold, if it were not used as an inflation-proof store of value, but rather only for its industrial uses, would certainly not be worth what it is today, since the industrial requirements for gold are far smaller than the available supply thereof.

In any event, while historically intrinsic value, as well as other attributes like divisibility, fungibility, scarcity, durability, helped establish certain commodities as mediums of exchange, it is certainly not a prerequisite. While bitcoins are accused of lacking 'intrinsic value' in this sense, they make up for it in spades by possessing the other qualities necessary to make it a good medium of exchange, equal to or better than commodity money.

Another way to think about this is to consider the value of bitcoin the global network, rather than each bitcoin in isolation. The value of an individual telephone is derived from the network it is connected to. If there was no phone network, a telephone would be useless. Similarly the value of an individual bitcoin derives from the global network of bitcoin-enabled merchants, exchanges, wallets, etc... Just like a phone is necessary to transmit vocal information through the network, a bitcoin is necessary to transmit economic information through the network.

Value is ultimately determined by what people are willing to trade for - by supply and demand.

In March 2013, the U.S. Financial Crimes Enforcement Network issues a new set of guidelines on "de-centralized virtual currency", clearly targeting Bitcoin. Under the new guidelines, "a user of virtual currency is not a Money Services Businesses (MSB) under FinCEN's regulations and therefore is not subject to MSB registration, reporting, and record keeping regulations." [2] Miners, when mining bitcoins for their own personal use, aren't required to register as a MSB or Money Transmitter. [3]

In general, there are a number of currencies in existence that are not official government-backed currencies. A currency is, after all, nothing more than a convenient unit of account. While national laws may vary from country to country, and you should certainly check the laws of your jurisdiction, in general trading in any commodity, including digital currency like Bitcoin, BerkShares, game currencies like WoW gold, or Linden dollars, is not illegal.

According to the definition of terrorism in the United States, you need to do violent activities to be considered a terrorist for legal purposes. Recent off-the-cuff remarks by politicians have no basis in law or fact.

Also, Bitcoin isn't domestic to the US or any other country. It's a worldwide community, as can be seen in this map of Bitcoin nodes.

Cash transactions offer an increased level of anonymity, yet are still taxed successfully. It is up to you to follow the applicable tax laws in your home country, or face the consequences.

While it may be easy to transfer bitcoins pseudonymously, spending them on tangibles is just as hard as spending any other kind of money anonymously. Tax evaders are often caught because their lifestyle and assets are inconsistent with their reported income, and not necessarily because government is able to follow their money.

Finally, the Bitcoin block chain is a permanent record of all transactions, meaning it can be mined for info at any time in the future making investigation, tracing of funds, etc much easier than with other forms of payment.

Bitcoins are not printed/minted. Instead, blocks are computed by miners and for their efforts they are awarded a specific amount of bitcoins and transaction fees paid by others. See Mining for more information on how this process works.