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.

Total circulation will be 21,000,000 coins. It'll be distributed
to network nodes when they make blocks, with the amount cut in half
every 4 years.

first 4 years: 10,500,000 coins
next 4 years: 5,250,000 coins
next 4 years: 2,625,000 coins
next 4 years: 1,312,500 coins
etc...

When that runs out, the system can support transaction fees if
needed. It's based on open market competition, and there will
probably always be nodes willing to process transactions for free.

Satoshi Nakamoto

Ce morceau d'histoire