What is schema markup (structured data)?

Schema markup is hidden code you add to a page that labels its content in a vocabulary search engines understand - telling Google which part is a business address, which is a review score, which is a product price:

• What it does - translates page content into machine-readable facts, so Google can interpret your page rather than guess at it.
• What it can earn you - rich results: star ratings, FAQ drop-downs, business hours and event details shown directly in the search listing.
• The common types for a small business - LocalBusiness for your address and hours, Product for items, FAQPage for question-and-answer content.
• The honest limit - schema makes you eligible for rich results; it does not guarantee them, and it is not a direct ranking factor.

Schema markup helps Google understand and display your page, but it earns nothing if the underlying content is thin - get the content right first.