Warning issued to millions of Android owners over extremely costly mistake

ANDROID owners have been warned against signing into their Gmail account on a friend's phone as it could have some devastating consequences.

It may seem innocent but doing so is risky.

Gmail is much more than an email app.

It's all tied into your wider Google Account.

You may trust your friends with your account but what if their device is compromised or stolen by a hacker?

This would not only allow them to snoop through your emails, but it could let them sign into a whole host of Google services.

As an extra security layer, some Google sites will send a random number to your Gmail app.

This is to verify that it's you trying to sign in.

If a cyber thief has your friend's phone with your Gmail logged in they'll be able to gain full access to just about anything.

This includes signing in as you on Chrome and going through your personal history.

And even going on Google Maps to see your location history.

So it's a bit risky to leave your Gmail signed in on another person's device.

If you do need to check email on a phone that's not yours, it's better to go via the incognito mode in Chrome.

That way no data is stored once you close the browser.