BSB is a 6 digit numeric code used for identifying a branch of an Australian or New Zealand bank or financial institution. BSB stands for "Bank State Branch".
The first two digits identify the bank
The third digit identifies the state
The fourth to sixth digits signify the branch
For example, BSB: 062002
06 = NAB
2 = NSW
002 = Pitt Street & Martin Place, Sydney 2000
The major banks have the following identification codes: