Social proof is an important component in the credibility of a website. No one wants to be the only one buying the product, so people naturally want to see that others have bought the same thing before them and were happy with it.
There are multiple ways to establish and provide social proof. Commonly, social networks, such as Facebook, Twitter, Instagram or Pinterest are used as sources of social proof, by linking the Likes, or tweets or other similar indicators so users can see how many other customers there are and what they think of the product. Another method can be reviews and rating the products on the website itself. Customer testimonials and case studies are the way to provide ample social proof and are mostly used in B2B context and setting.