What is phishing?
The messages usually contain links or attachments which, if you click on them, can install malware. This is a type of malicious software, which steals information. It can be so sophisticated that it works in the background to move your money, or even tricks you into thinking that you need to re-enter your security details. Then, the fraudster captures your information when you re-enter it.
Fake websites will normally ask you to confirm your security details in full, rather than the selected pieces of information. The fraudsters then use your details to access your account(s) and steal your money.