Any individual having a bank account must have used passbook. This is a book provided by the bank to keep the records for transactions of a savings or current bank account. Earlier, passbooks were managed by a bank personnel or teller who used to write the transactions on the book. The teller was supposed to sign on the book confirming that the transactions were authorised by the bank. However, this also had a scope for human errors and misrepresentation of facts.
To eliminate these factors, modern passbooks were designed to be easily integrated with computers. Now, you do not have to go to a teller for writing the transactions and sign the book. There are automated tellers installed in banks that record the transactions as per your account information. Modern passbooks carry a Bar-Code that contains your account information. You just have to insert the book into the machine and it will write the transactions accordingly.
However, this was just the starting of the automation of banking processes. Another new concept which is being highly popular these days is the M Pass Book.