There are many kinds of tactics used by phishers. Not all of them say that your account has been hacked.

This real-world example plays on the idea of an uncollected parcel to get you to click the link.
Usually, the scammers send an email pretending to be from a service like Paypal or Amazon. They try to get you to follow a link which leads to a fake login page.
Phishing emails can be very sophisticated, and there is no one way of detecting them.
There are, however, a handful of common giveaways a phishing scam might have.
