Hello everyone, I've been reading a bit of the bitcoin wiki and I'm really impressed by the technical details.

However, I have one question: how is the balance of a single address or an account calculated?
AFAICT, this is the sum over all transactions in the longest chain involving that address, correct?

If yes, this leads to the next question: won't the amount of computation needed to scan through the
entire chain become prohibitive at some point? Especially if the number of transactions increases at
a similar rate as, e.g. the global hash rate?

Florian