In the few years it has been around, Google has grown into a powerful force for customer reviews. Any business wishing to build its social proof needs to have good reviews on Google in order to be successful.

The site’s power comes from its connection with Google Search, the most popular search engine, and Google Maps. Whenever someone does a Google search, or uses Google Maps, reviews for the business get displayed.

Study by DigitasLBi’s Connected Commerce shows that Facebook influences 52% of consumers’ online and offline purchases. Users are no longer just socializing on Facebook: they're also sharing reviews and recommendations. Along with Google, Yelp, and TripAdvisor, Facebook is ranked one of the top sites that customers use to review businesses.

Facebook reviews moved to a new recommendation format and away from the standard 5-star rating about 2 years ago. Customers wishing to review a business on Facebook are asked "Do You Recommend {Business Name}?" and answer by clicking "Yes" or "No".

Yelp is a popular online directory for discovering local businesses ranging from bars, restaurants, and cafes to beauty and fitness, health, and home services.

Yelp has a strong social aspect and encourages its users to leave written reviews, star ratings, and photos of their experience with each business they visit. And the reviews can easily sway these people’s opinions: to go or not to go. Remember what we mentioned about social proof at the party: A restaurant will need good buzz - good reviews on Yelp - to build its social proof.