Who's Following You Around via Your Smartphone?

You may think you're alone, but there's a good chance a handful of apps on your smartphone are closely following your every move.

This week, rideshare giant Uber faced social media backlash after updating its app to include the ability to track a user's location, regardless of whether or not the app was open.

Robert Siciliano, CEO of IDTheftSecurity.com, told NBC News the reason why companies like Uber — and plenty of other app makers — want to follow your move "boils down to functionality and long-term use."

"When you go to use it [the app], they want you to be able to instantaneously have access to all of its features," Siciliano said. "Let's just say you have the app set to only track you when you are using it. When you go to use it, there may be a delay before the app becomes effective. It's in that time frame you may close the app, forfeit it and not use it."

If users opt to allow Uber to collect their data, the company says it will do so from the time the app is open until five minutes after a ride is completed.

Uber's rationale is that this will "improve pickups, drop-offs, customer service, and safety."

But not everyone is thrilled with the idea. With "always" and "never" as the only options, some users have lamented the lack of a "while using" option.

"Many people have raised concerns about this change, both questioning Uber's need for post-ride tracking and the change away from user control," a blog post from the Electronic Frontier Foundation said. "These concerns are quite understandable — there are many legitimate reasons that a rider would want privacy in their final destination, perhaps stopping the ride a block or three away from their true destination."

Almost every app maker would love to have permission to follow your every move, even when you're not using it, Siciliano said.

"They will track your location and get as much information about you as possible," he said. "All of that metadata is being bought and sold every day. If they could get your blood type, they would."

While you'd have to check each app's privacy policy to determine who is actually using your data for financial gain, there's a simpler way to just opt out.

On an Android smartphone, go to "settings" and then choose "apps." From there, you can choose each app and go to "permission" and "location" to see who's following you.

For iPhone users, go to "settings," "privacy" and "location services" to choose which apps you want to allow to track you.

While it might not be that big of a deal to some people, Siciliano said it's worth taking charge of your privacy.

"I turn off everything with the exception of maps and my runner's app," he said. "Some apps are tracking location and I see no reason why."