Google Fiber's TV service is now delivering targeted ads based on subscribers' viewing history, the company said in a forum post on Friday.

"In the next few weeks, we’ll be starting a small trial of this type of capability with our Fiber TV subscribers in Kansas City, KS and Kansas City, MO," the Google Fiber statement said. "These ads will show during existing ad breaks, along with national ads, on live TV and DVR-recorded programs. Fiber TV ads will be digitally delivered in real time and can be matched based on geography, the type of program being shown (e.g., sports or news), or viewing history."

Customers will see the targeted TV ads unless they opt out. Google provided instructions for opting out using the TV remote control.

"Once you’ve opted-out of commercials based on TV viewing history, Google Fiber will not collect any information for advertising purposes," Google told Ars. Google could still collect information for other purposes.

Google's website explains what kinds of targeted ads viewers may see. "For example, an advertiser that advertises on football games may want to deliver an ad to households that regularly view football games, even when they are viewing other programming," Google says. "Interest-based ads are based on shows you watch on Fiber TV. They are never based on or delivered to content that's rated as children's content."

Comcast also delivers cable TV ads based on customers' viewing habits, giving the customers the option to opt in or opt out of such targeted ads.

AT&T delivers targeted online ads based on subscribers' Internet browsing habits, unless customers pay a higher price for service. Google is apparently not doing that. "Targeted ads will not be tailored from customers’ Web surfing behavior, the company said," according to The Kansas City Star.