Hackers go "smishing" with Text messages (SMS) designed to trick you into entering your account ID and password into a fake webpage. Armed with your credentials, they can steal your identity!
In this example, the message asks you to confirm your Apple ID, claiming it is about to expire. If you click the link, you are taken to a webpage that looks real. But the hacker steals your ID and password if you enter them. Sometimes the webpage will ask for your credit card information, too!
Once hackers have your account information, they can try compromising other accounts you own. For example, they could try resetting "forgotten" passwords from bank and credit card accounts using your email service.
Smartphones are becoming more frequent targets now that they are used for more and more Internet activities. Be careful out there!