Smartphones were once a luxury reserved for the wealthy and technologically savvy. But steadily declining prices have put the devices in the hands of the masses, with three-quarters of U.S. consumers now using them.

Despite this rising popularity, few people appreciate the risks of carrying a mini-computer in their purses or pockets, and that can expose you to everything from identity theft to real live robberies. Here are 5 things you should know about your smartphone.

Your phone is a tattletale. The global positioning system on your phone is a marvelous perk when you're trying to find the nearest gas station or negotiate your way through rush-hour traffic. But it also knows where you are when you're taking a picture or just hanging out in a bar.

Why would you care? Because the "find my phone" app could help your crazy ex stalk you, while the photos that you posted on Facebook include "metadata" that shows where you were when you were taking each and every shot. That means an opportunistic crook can find the new big-screen TV that you thoughtfully posted photos of before the Super Bowl, and take it while you're busily posting photos from your Hawaiian vacation.

Advertisers are also using that metadata to figure out where you drive and shop and predict when you're most likely to be susceptible to a product pitch. If you don't want any and every tech-savvy stalker to know where you are and where you've been, manage the GPS settings by either turning them off for certain functions or turning the GPS off completely until you want to use it to find something.

WiFi is watching. Most phones automatically search for a WiFi network when you're out, which saves you data-usage charges when you want to check Instagram or email. But public WiFi systems aren't secure, and a good hacker can pick up your passwords when you connect in public places. Clearly, this is not the setting to do your mobile banking. And, for people who like to use one password for every account, a public WiFi hotspot is a dangerous place to sign on to anything.

Your data is vulnerable. If you do more than make and take calls on your smartphone, it's highly likely that it has stored a ton of data about you, from saved passwords and past web searches to contact information for all of your friends. Phone applications that store your payment data (so you can buy coffee without a card) and other private information add to the mix, making a lost phone a risk for credit or identity theft. Yet phones slip out of pockets and get left on desks and counters all the time. Make it harder to steal your data by going into the settings and plugging in a password.

Phones get "phished." The same hazards that apply when getting random "click to verify" emails or "check out this funny photo" messages also apply when you're using your smartphone. Click on the wrong site and malware can hijack your phone just as easily as it can hijack your laptop. This phone is a computer that goes everywhere with you. Be just as cautious - actually, be more cautious -- with your phone as you are when using your computer at home.

Erase before trading. If you're getting a new smartphone and want to sell or give away the old one, make sure you return the phone to the factory settings before you do, says Stacey Vogler, managing director of insurance site Protect Your Bubble. Restoring the factory settings will erase personal data and stored passwords, she says.