Find a teen, find a cellphone.

According to a Pew Internet study released in August 2012, 78 percent of American teens have a cellphone. Parents know their teens aren’t using their devices to have long-winded conversations, so what commands their time?

Here are five new apps are growing in popularity and important for parents to know about because many come with maturity warnings and are rife with problems.

Kik

Kik is a messenger app. It boasts 100 million users and seems like a free texting app that will be able to connect users with their friends, ideal especially for teens that don’t have a cellphone plan and use an iTouch or tablet device.

The problem? There are no parental controls and the app has become a place to swap sexts. It’s very easy for an unsuspecting users to be solicited for nude photos. If you hear your teen say “kik me” to another, this is the app they are talking about.

Vine

Vine exploded in 2013. The concept of making and sharing six-second videos isn't bad. It’s been used by celebrities, breaking news coverage, and is famous for its incredible stop-motion videos.

However, the app quickly earned a maturity warning and 17+ rating from Apple when pornography appeared as an “editor’s choice” video in January 2013. While that video was removed, nudity is still allowed and profanity is rampant on the app.

Keek

Where Vine is the place for short videos, Keek is the place for longer videos. While the app has not confirmed to other media outlets if it pays celebrities to market for them, Kendall Jenner and her Kardashian sisters are some of the biggest users, making it desirable for teens to be a part of it. When teens join, they may discover pornography and profanity. There are no privacy settings on Keek, meaning adults can subscribe to a child’s content and contact them.

Ask.fm

An app ripe for cyberbullying, which is growing in popularity among teens, is Ask.Fm. The premise is simple: users create profiles, with the idea they will answer questions from their friends. But the problem arises when anyone can submit an anonymous question. Also, Ask is often used for bullying and posting cruel statements on user’s timelines.

Whisper

Similar in nature to the popular blog Post Secret, Whisper is an app where people post questions and confessions as a text over a picture. The Whispers are made public and someone can like or comment on an image or even private message on a post. In its terms of service, Whisper discourages posting material that is sexually suggestive or violent or that encourages eating disorders and suicide, but such content is often on the home screen of the app.

Some posts written include “anyone out there into tall men,” “super bored would love to talk, 17f” and several are not fit for print. The app has a 17+ rating from the Apple App Store.

“The ability to private message within those apps or ask with a veil of anonymity causes issues for bullying, predators grooming.

“These are all tools to get kids,” said Ben Horsley of the Granite School District in Utah. “Make sure you are on a regular basis having a discussion about what’s appropriate.”

Horsley advised parents to take the phone away at night, and to control what is downloaded and deleted on teen's and tween’s devices. Or get the teens a regular flip phone so the teens can text and call but not download apps.