A Rich Result is a search result that contains additional information beyond the standard display. This can include star ratings, a preview image, a price, availability, or the cooking time for a recipe. This additional information makes the search result stand out more from the crowd than simple text entries. It also gives potential visitors an idea of what to expect.
Rich snippets are made possible by structured data—that is, technical markup for the content embedded in the source code. This data provides search engines with clear indications of what content is on the page and how it should be categorized. This allows the search engine to recognize, for example, that a “5” on the page is not just a number, but a rating. However, Google itself decides whether to display this additional information.