How many apps do you have on your smartphone? Probably more than you think. A survey by App Annie shows that the average smartphone user has in the neighborhood of 80 apps on their phone and they use less than half of them.

Big deal, you think? What's the harm? Maybe I'll get back to that game one of these days. Be aware, "Zombie Apps" can cause problems.

Apps that haven't been updated in a long time likely have security holes that hackers can take advantage of to install malware or adware on the phone. They could even take information from your phone including name, address, email and phone number.

Many apps change hands. One company might buy out another company and they'll get all of that information with it. Those are both good reasons to make sure your apps stay up to date and if the app doesn't get updates any longer, it's probably best to delete it. Deleting apps is quite simple: just touch and hold the app on iPhones and iPads until an 'x' appears next to it. With Android devices you just hold your finger on the app and swipe up to remove or uninstall it.

It isn't good enough in some cases to just delete the app. If you signed up for an account when installing the app, you should go online and delete that account. That's easier said than done, but you should check settings in Facebook, Gmail and Twitter to find apps you've signed up for using those social and email accounts.

If you're not satisfied you've gotten them all, search your email inbox for "verify" or "confirm". In many cases when you sign up for an account you'll get an email with a link to verify your email address and your account. You'll need to jump through a few hoops to delete those accounts but if it's a spammy app you wish you'd never downloaded, it's worth the trouble to locate your account and delete it.

It's also a very good idea to consider what you're giving up when you download any free app. You might get to play a free game or you might get 10% off at a restaurant, but ask yourself "is my personal information worth more than an order of potato skins?"