Some people are wondering who is behind the ads. One consumer group is warning that many of them are scams. Consumers might want to think twice before they click.
When you go online you probably run into many paid ads. Some of them can be tempting, offering free phones or discount hotels.
"If you're on a website, if it looks shady, if it looks too good to be true, it probably is. So, go back. Don't give out information about yourself," says Jarrod Agen from the Alliance Against Bait & Click.
Agen says a simple search for a favorite brand name could lead you to an unrelated website, one that may be out to get your personal information or even infect your computer with spyware.
"It can even happen with a ring tone. You go in and type in 'ringtone' and all these different free ringtone ads pop up, and it's trying to deceive you into getting your personal information," he explained.
Agen says kids may be especially vulnerable.
"They end up going online and they're putting in their cell phone information in to who knows what website this is."
For example, ABC7 found one ad offering two free i-Phones. But, the actual website was a marketing company that asked for a lot of private information including name, address, email, date of birth, and phone number.
It even asked if the user has wrinkles or uses teeth whiteners.
In the end the user has to buy stuff to get the "free" i-Phones.
"Once you've given up that kind of information it's never-ending. You may get pop-ups ads. You may get spyware. You may get virus'. All these things open up," Agen says.
McAfee, the anti-virus software company in Silicon Valley did a study that found many online ads do lead to websites that could infect your computer with malicious software.
"Overall, around seven percent of those links do contain dangerous software. And, with certain keywords, whether it's 'free,' 'ringtones', 'screensavers,' there's a number of keywords, that risk goes up to 60 to 80 percent," says Brent Remai with McAfee, Inc.
Remai told ABC7, "Most people don't realize this, but the Internet serves up over 4 billion risky sites to users every month."
Search engines like Google and Yahoo do say they screen ads to prevent problems. Google says it continually reviews ad words to make sure they accurately represent advertised products. Yahoo says it has strict guidelines against improper use of trademarks and company names.
Hagen says the quickest remedy is to only click on official websites for products you want.
"What we advise people is, the less you click on these ads, the sooner they'll go away," he says.
Of course, not all ads are risky and there are ways to protect yourself from possible scams.
Click here for more tips on how to detect which websites are safe and which are not.