Phishing, The emails the bait and you are the fish
Online banking scams involve what is know as "Phishing". The basic idea is that the scammers send out bulk emails to millions of people worldwide pretending to be a large well know financial institution. The email would normally indicate that you are required to update your personal details. The link in the mail then takes you to what looks like your bank but it is however masked and you are really now on the scammers web page where they can store any sensitive information that you enter on the page. This information could give them login details and bank account information which can be used to steal money from your accounts.