It’s hard to be active online without sharing personal information about yourself. There’s some data you may know never to make public—like your Social Security number and home address—but sharing facts like your birthday or your parents’ names can also open you up to identity theft. Mental Floss and Discover put together this list of places hackers go to find private information hiding in plain sight.

1. Social media

Entering as much personal information as possible on your social media pages makes hackers’ jobs a lot easier. Many social networking sites ask you to fill out basic information about yourself, such as where you live, where you work, your birthday, and who your family members are. You may not see the harm in sharing this data with your circle of friends, but in the hands of the wrong person, it can be used hack into your accounts and steal your identity. Even if your profile is set to private, limit the identifying information you share on social media.

2. E-commerce websites

Shopping on the internet is convenient, but storing all your credit card information, including the expiration date and security code, in one place can leave it vulnerable to hackers. Instead, commit those numbers to memory or keep your wallet handy when you want to do some online shopping.

3. Quizzes

It’s easy to let your guard down when taking fun quizzes online, and that’s what hackers are counting on. Some quizzes ask personal questions—such as where did you grow up?, and who was your childhood pet?—similar queries to the security questions you find on a bank website’s login page. Instead of deleting that information once it’s entered, many quizzes save your answers, which means they can be used by hackers for identity theft. The next time you take a personality quiz online, think carefully about what your answers may reveal about you.

4. Search engines

Sometimes all a hacker needs to do to find sensitive information about you is search your name. The easiest way to minimize your presence in search engine results is to find web pages with your name and delete them (or ask for them to be deleted) when possible. If you see a search result for a page you know you’ve already gotten rid of, you can submit a request directly to the search engine asking them to remove the out-of-date information.

5. Fitness trackers

Even the wristband you use to track your physical activity can be exploited. Information like your heart rate and daily step count may not be of much use to hackers, but the movement of your hands is a different story. According to one study, if your wear a fitness tracker while entering your smartphone passcode or ATM PIN number, hackers can use that motion information to guess your code within a few tries with more than 90 percent accuracy. So when you’re about to do something you wouldn’t want a hacker to see, make sure you’re not wearing a device that tracks your every move.

6. Digital trash bins

Just because you’ve moved a file to the trash icon on your desktop doesn’t mean it’s safe from hackers. When you “delete” information you no longer want on your computer—such as tax documents or personal photographs—you’re really just deleting the file system without deleting the actual data. With the right software, hackers can recover whatever’s in your trash bin and use it for their own gain. If you really want to delete your digital trash, you need to wipe your hard drive clean.

With all this information floating around the Internet, it’s important to have security measures in place. With Free Social Security number alerts, Discover monitors thousands of sites on the Dark Web and alerts you if they find your Social Security number. The best part? It’s free for cardmembers who sign up. Learn more at Discover.