海角大神

Perhaps one day you have a particularly tasty slice of pizza and decide to rate the restaurant on Google Plus Local.

鈥淢mm, delicious slice!鈥� you write, adding a four out of five star rating.

The next day, don鈥檛 be surprised when you get to Google and see an ad for that pizza joint with a glowing recommendation 鈥� from you.

Google announced a change to its Terms of Service Friday, letting Google users know that their follows, comments, shares, ratings, and +1s could end up on advertising.

鈥淲e want to give you 鈥� and your friends and connections 鈥� the most useful information,鈥� Google says. 鈥淩ecommendations from people you know can really help.鈥�

When you hit +1 on an album in Google Play or rate a coffee shop on Google, your Google-using friends may see your recommendation or +1 on an advertisement for those products or businesses across Google services, ranging from Google Maps to YouTube. These Terms of Service officially begin Nov. 11.

Though Google has a rosier view on endorsements, anyone who has taken a business course may see this as thinly veiled word-of-mouth marketing, an advertising technique that relies on customers to serve as self-motivated ambassadors of a product. The idea is that people are more likely to buy a product or frequent a business if someone they trust recommends it to them. It鈥檚 an advertising tactic that has been around nearly as long as business itself, but has especially ballooned in the Internet age with services such as Yelp and FourSquare.

The difference is that this feature is now built into the Google Plus social network, and people must opt-out if they do not want their words used by advertisers.聽 Google makes this relatively easy 鈥� under 鈥淎ccount Settings鈥� in Google Plus, just hit 鈥淥ff鈥� where it says Shared Endorsements. You can also choose to limit who can see your endorsement in an ad, so instead of showing up publicly, it may show up just to people in one of your Circles.

It also only happens when you actually take an action, like +1ing a link or rating a restaurant, and anyone younger than 18 is not included in the program.

This news rolls into a growing debate on privacy extending from Facebook鈥檚 new, sophisticated Graph Search to revelations about the NSA鈥檚 surveillance reach. With social networks reaching nearly one in four people worldwide, this conversation won't likely end anytime soon.