Protection from Vandalism
Weve talked a lot about what information in Bitcoin is public knowledge, but what exactly needs to be kept private? Each user must keep secret the information that allows them to render digital signatures for their accounts otherwise a thief could announce transactions to remove money from their accounts. This information is kept inside of each users wallet, which is stored as a file on their computer. It is highly recommended that you encrypt your wallet and make periodic backups.
This is better.
Initial Issuance
To bring coins into circulation, the first certain number of blocks in the block chain represent newly issued Bitcoins, which are used to pay those who help build the chain (rather than transaction fees). This mechanism is policed in the same manner as everything in Bitcoin: via the consensus mechanism. Even though individual Bitcoin users may wish to counterfeit, no user would desire others to counterfeit, and so they reject a block chain that includes new Bitcoins past a certain limit, which is agreed to be 21 million Bitcoins. The fear of non-recognition by other auditors means that no individual would ever accept as payment a coin that is known to be counterfeit.
This is worse.
Initial Issuance
To bring coins into circulation, those who generate a new block are rewarded with newly issued Bitcoins in addition to any transaction fees. The amount of new coins awarded will decrease over time eventually reaching zero when there are 21 million total Bitcoins.