Schema markup is vocabulary from Schema.org that you embed in your HTML to explicitly tell search engines what your content represents—whether it's a product, recipe, local business, article, event, or one of 800+ other types. Instead of Google guessing that "4.8 stars" means a rating, schema tells it directly. You typically implement it using JSON-LD format in a script tag, though Microdata and RDFa also work. The SEO value shows up in three ways. First, rich results: properly marked-up pages can display star ratings, pricing, availability, breadcrumbs, FAQ accordions, and how-to steps directly in search results. These enhanced listings occupy more screen real estate and draw more attention than plain blue links. Second, better understanding: schema reduces ambiguity for Google, especially useful for entities with multiple meanings or complex offerings like SaaS products or professional services. Third, eligibility for specialized features: certain SERP elements like recipe carousels, job postings, and local business panels require schema to appear at all. We see the biggest impact on e-commerce sites (product schema), local businesses (LocalBusiness schema with NAP data), and content publishers (Article schema with author and date information). For Ottawa-area clients, adding LocalBusiness schema with proper address and service area markup helps with map pack rankings and Knowledge Panel accuracy. What matters most is accuracy and completeness. Google ignores or penalizes schema that doesn't match visible page content—don't mark up five-star reviews you don't have or claim to be open 24/7 when you're not. Use Google's Rich Results Test and Schema Markup Validator to catch errors before deployment. Focus on the schema types most relevant to your business model rather than marking up everything possible. At Ottawa SEO, we prioritize breadcrumb, organization, and content-type schemas as baseline implementations, then layer on specialized markup based on what each page actually contains and what rich results we're targeting in competitive SERPs.