175 million. On average, that's how many tweets were sent daily in 2012. The total number of tweets sent since the site launched just seven years ago is in the hundreds of billions.
Twitter, of course, is one of many social networking sites that retailers have worked to leverage. Facebook has also been a behavior-changer for many, and companies are still developing their best practices for how best to use these networks to communicate with their customers.
Many retailers are using social media with successful results, as illustrated in this infographic. It's interesting how different types of retailers are using different networks based on their business and audience - for instance, the craft retailer Michael's taking advantage of the visual nature of its product selection on the visually driven Pinterest.