You don't have to keep your pc on. I received BTC many times while my PC was off.
Tech Explanation: What you store in your wallet are private keys to move the money. Money is not actually stored in the wallet. The transaction gets verified on the blockchain. If you lose all your private keys, you cannot move the money anymore and the money is forever stuck in that account. This has happened to a few users in the past.
Are you a techie? So the private keys are in a dictionary: dictionary
? I think so, meaning each private key has a look-up table value (amount in BTC) associated with it. So lose the keys, lose that value of BTC that is forever lost from the total number of bitcoin mined. See also please my latest question. Thanks for educating a noob!
We are two young americans, my wife and me.
If a key is lost the coins are stuck forever on the block chain (a database in all clients). All owners have a public and private key. If you are unfamiliar with public key cryptography this can get quite confusing, but it's a two key cryptographic system in which you need the private key to encrypt or sign. The private key gives you the power to authorize or authenticate.
An electronic coin is a chain of digital signatures which is stored inside the blockchain (the database). An illustration of a bitcoin:
If you press "send" a hash of the previous transaction is signed and the public key of the next owner and adding these to the end of the chain. If you are Owner 2, you'll see the transaction
can only occur if it is signed with owner 2's private key (your private key). The public key is commonly known in public key cryptography, but private key not.
But let's say you type a legal bitcoin address, then what? I bet the bitcoin just sits there until somebody 'claims' this address?
I do not know if this is possible or not.
Further, can you 'reverse' or cancel a bitcoin transaction *before* it is received by the receiver?
No, you cannot cancel a transaction. The only reason a transaction fails is if the other clients do not accept it.
Finally, consider this: can two people have the same public key?
Technically this is possible, but it is similar to the chance of winning one hundred lotteries in a row.