SEO has included the concept of structured data since 2011 - ever since Google, Bing, Yahoo! and Yandex got together to create a standardized list of attributes and entities which they all agreed to support, and which became known as Schema.org. Unfortunately, there's still a lot of confusion around what structured data really is, what it’s for, and how and when to implement structured data for SEO purposes. A survey carried out last year by Bing found that only 17% of marketers are using (or were planning to use) Schema.org structured data markup.