Smartphones -- every kid has one these days. But no matter how hard parents try, it's getting harder and harder to keep track of what their children are doing with the phones.
In fact, it may be next to impossible to tell there's trouble, even when it's right in front of them.
That's because if you take a look your child's smartphone screen, all the apps may seem standard. But some of them may just be a facade.
"There could be a whole other world lurking behind what you see on the surface," said Tom Jelneck, president of On Target Web Solutions.
Jelneck said there's a long list of apps designed to hide photos and videos on phones.
"These apps are made to look like normal apps, so you as a parent, you pick up your child's phone, you dig through it, everything checks out," Jelneck said.
Parents News 6 anchor Matt Austin spoke to said this was disconcerting.
"That's like the scariest thing ever," Evelyn Castillo said.
"Oh, wow, never even heard of that," Megan Starling said.
"I think I'd be quite nervous as a parent," Janet McDermott said.
Several are difficult to detect. One app, called Best Secret Folder, looks like a utilities folder. But as soon as you click into it, it asks for a passcode to let you into the hidden vault.
But there's another one that's even more difficult to detect.
"Check this out. You ever seen this calculator?" Austin asked.
"Oh yeah, a buddy of mine had it," Andres Castillo said.
"Oh, so you know? How would a parent ever know?" Austin asked.
"It's a calculator that looks like a calculator and is a calculator, but if you input like a code, it's basically, you can store stuff on there," Andres Castillo said.
"Like naughty pictures," Austin said.
"Yeah, and that's what he did,"Andres Castillo said.
"You're not allowed to have a phone ever," Evelyn Castillo said to the couple's 3-week-old baby girl, laughing.
Yet another app is called Audio Manager. It looks like something you would use to manage music on your phone, but what happens with this one is someone can click it in a certain sequence and that gets you into the vault.
Apps like these have been known to get kids in major trouble before.
Back in 2015-- school officials discovered a sexting scandal that involved more than 100 students at a Colorado high school. Those officials say several hundred photos were found-- in apps just like these.
"It's becoming increasingly more difficult for parents and for anyone to supervise what's happening digitally with their kids," Jelneck said.
But there are a few ways you can keep on top of what they're downloading.
First, you can add your child to your Apple ID, but you'll want to do that just for iTunes content so you can monitor their downloads. They'll still need their own Apple ID for other phone functions to avoid messing up your account.
"When you sync the phone or that child downloads an app, it'll actually download the same app to your phone," Jelneck said. "So if you're digging through your own phone and you notice there's a new app on here, 'Where did this come from?' and you can do a quick Google search and see what this app is all about."
If you choose to set them up on their own Apple ID, you can keep track of what they're doing by setting up family sharing. Then you can see what's they've downloaded-- and download them onto your own device to check out.
You can do something very similar-- if you have Android phones too.
Still -- Jelneck said the best defense is knowing more than your kids do.
"You, as a parent, it's time to get your nose into tech stuff. You have to know what's going on and stay vigilant," Jelneck said.