Excellent choice of a first project, nice work. I had planned to do this exact thing if someone else didn't do it, so when it gets too hard for mortals to generate 50BTC, new users could get some coins to play with right away. Donations should be able to keep it filled. The display showing the balance in the dispenser encourages people to top it up. You should put a donation bitcoin address on the page for those who want to add funds to it, which ideally should update to a new address whenever it receives something.

Bitcoins have no dividend or potential future dividend, therefore not like a stock. More like a collectible or commodity.

Simplified Payment Verification is for lightweight client-only users who only do transactions and don't generate and don't participate in the node network. They wouldn't need to download blocks, just the hash chain, which is currently about 2MB and very quick to verify (less than a second to verify the whole chain). If the network becomes very large, like over 100,000 nodes, this is what we'll use to allow common users to do transactions without being full blown nodes. At that stage, most users should start running client-only software and only the specialist server farms keep running full network nodes, kind of like how the usenet network has consolidated. SPV is not implemented yet, and won't be implemented until far in the future, but all the current implementation is designed around supporting it.

In this sense, it's more typical of a precious metal. Instead of the supply changing to keep the value the same, the supply is predetermined and the value changes. As the number of users grows, the value per coin increases. It has the potential for a positive feedback loop; as users increase, the value goes up, which could attract more users to take advantage of the increasing value.

Simplified Payment Verification is for lightweight client-only users who only do transactions and don't generate and don't participate in the node network. They wouldn't need to download blocks, just the hash chain, which is currently about 2MB and very quick to verify (less than a second to verify the whole chain). If the network becomes very large, like over 100,000 nodes, this is what we'll use to allow common users to do transactions without being full blown nodes. At that stage, most users should start running client-only software and only the specialist server farms keep running full network nodes, kind of like how the usenet network has consolidated. SPV is not implemented yet, and won't be implemented until far in the future, but all the current implementation is designed around supporting it.

We're not "on the lookout" for double spends to sound the alarm and catch the cheater. We merely adjudicate which one of the spends is valid. Receivers of transactions must wait a few blocks to make sure that resolution has had time to complete. Would be cheaters can try and simultaneously double-spend all they want, and all they accomplish is that within a few blocks, one of the spends becomes valid and the others become invalid. Any later double-spends are immediately rejected once there's already a spend in the main chain.

Announcing version 0.3 of Bitcoin, the P2P cryptocurrency! Bitcoin is a digital currency using cryptography and a distributed network to replace the need for a trusted central server. Escape the arbitrary inflation risk of centrally managed currencies! Bitcoin's total circulation is limited to 21 million coins. The coins are gradually released to the network's nodes based on the CPU power they contribute, so you can get a share of them by contributing your idle CPU time.

Currently, paying a fee is controlled manually with the -paytxfee switch. It would be very easy to make the software automatically check the size of recent blocks to see if it should pay a fee. We're so far from reaching the threshold, we don't need that yet. It's a good idea to see how things go with controlling it manually first anyway.

Any owner could try to re-spend an already spent coin by signing it again to another owner. The usual solution is for a trusted company with a central database to check for double-spending, but that just gets back to the trust model. In its central position, the company can override the users, and the fees needed to support the company make micropayments impractical. Bitcoin's solution is to use a peer-to-peer network to check for double-spending. In a nutshell, the network works like a distributed timestamp server, stamping the first transaction to spend a coin. It takes advantage of the nature of information being easy to spread but hard to stifle.

The network is robust in its unstructured simplicity. Nodes work all at once with little coordination. They do not need to be identified, since messages are not routed to any particular place and only need to be delivered on a best effort basis. Nodes can leave and rejoin the network at will, accepting the proof-of-work chain as proof of what happened while they were gone. They vote with their CPU power, expressing their acceptance of valid blocks by working on extending them and rejecting invalid blocks by refusing to work on them. Any needed rules and incentives can be enforced with this consensus mechanism.

I'm sure that in 20 years there will either be very large transaction volume or no volume.

The traditional banking model achieves a level of privacy by limiting access to information to the parties involved and the trusted third party. The necessity to announce all transactions publicly precludes this method, but privacy can still be maintained by breaking the flow of information in another place: by keeping public keys anonymous. The public can see that someone is sending an amount to someone else, but without information linking the transaction to anyone. This is similar to the level of information released by stock exchanges, where the time and size of individual trades, the "tape", is made public, but without telling who the parties were.

Bitcoins have no dividend or potential future dividend, therefore not like a stock. More like a collectible or commodity.

Lost coins only make everyone else's coins worth slightly more. Think of it as a donation to everyone.

The recipient just needs to verify it back to a depth that is sufficiently far back in the block chain, which will often only require a depth of 2 transactions. All transactions before that can be discarded.

We're not "on the lookout" for double spends to sound the alarm and catch the cheater. We merely adjudicate which one of the spends is valid. Receivers of transactions must wait a few blocks to make sure that resolution has had time to complete. Would be cheaters can try and simultaneously double-spend all they want, and all they accomplish is that within a few blocks, one of the spends becomes valid and the others become invalid. Any later double-spends are immediately rejected once there's already a spend in the main chain.

Subscription sites that need some extra proof-of-work for their free trial so it doesn't cannibalize subscriptions could charge bitcoins for the trial.

New transaction broadcasts do not necessarily need to reach all nodes. As long as they reach many nodes, they will get into a block before long. Block broadcasts are also tolerant of dropped messages. If a node does not receive a block, it will request it when it receives the next block and realizes it missed one.

I'll try and hurry up and release the sourcecode as soon as possible to serve as a reference to help clear up all these implementation questions.

There are two ways to send money. If the recipient is online, you can enter their IP address and it will connect, get a new public key and send the transaction with comments. If the recipient is not online, it is possible to send to their Bitcoin address, which is a hash of their public key that they give you. They'll receive the transaction the next time they connect and get the block it's in. This method has the disadvantage that no comment information is sent, and a bit of privacy may be lost if the address is used multiple times, but it is a useful alternative if both users can't be online at the same time or the recipient can't receive incoming connections.