Keeping track of your teen's smartphone activity can be challenging if you're not familiar with the latest apps. Bullying is also happening in various messaging apps.

Here's a list of apps every parent should know:

  1. Apple's App Store and Android's Play Store both have pages of file lockers. Apps like Secure Vault for Apple use encryption and passcodes to lock away files from prying eyes. Without the secret code, folders of photos, videos and notes can be locked away from parent's view.
  2. KeepSafe, another app to lock up potentially revealing photos, goes one step further. If someone tries to break-in, without the correct security code, the app captures a photo using the front-facing camera.
  3. Another example of a file vault is Calculator%. The app works like a regular calculator, but when your child enters period period, a hidden menu appears. Inside, users can secure files, documents, illicit photos or more from those without the code. There's even an emergency button that quickly puts the adding machine back on the screen.
  4. ASKfm is a social networking app gaining traction. Users ask questions and receive back anonymous replies. This often results in bullying and has led to numerous cases of suicide. The app's owners have promised to help prevent bullying.
  5. Snapchat is perhaps the most popular. The photo and video-sharing app caught the attention of many parents when it was released a few years ago. Taking a photo, adding a caption, graphics, and then sharing with your friends for a few seconds. While the app does delete the photos, screenshots can be taken and photos a child thought was private, may not be. 
  6. LINE is a fast-growing messaging app capable of sharing photos and video as well as free texting and video chat. Among the dangers for parents, this app includes various in-app purchases that may lead to surprises on a parent's credit card. The app suggests you need parental permission, but doesn't verify.
  7. kik. has become an instant messaging app for sexting. Without authentication or parental controls, users can hide behind the app lying about their identity, age or location. 
  8. BurnNote is a messaging app where users exchange super secret messages. The feature to send links to any user, even if not using the app, may cause curious recipients to get trapped in the app. 

Messaging apps generally promise photos, text, or videos are deleted after viewed by the recipient. Unfortunately, there's just no way to guarantee all messages are completely removed.

Many smartphone apps bring danger. Parents should spend some time familiarizing themselves with the apps to avoid surprises or child bullying.

Follow KING 5 Technology Reporter Brian M. Westbrook on Twitter: @BrianWestbrook