Meta tags are snippets of code in a page's HTML <head> section that describe the page's content to search engines, browsers, and social platforms. They don't appear on the page itself—they work behind the scenes. The critical ones for SEO are the title tag (technically not a meta tag but grouped with them), meta description, meta robots, and canonical tag. The title tag sets what shows in search results and browser tabs—keep it under 60 characters to avoid truncation. The meta description is your 155–160 character pitch that appears below the title in Google results. It doesn't directly affect rankings but drives click-through rate, which does. Meta robots tells crawlers whether to index the page or follow its links—useful for staging environments, thin pages, or duplicate content you want to suppress. The canonical tag points to the preferred version of a page when you have near-duplicates, preventing self-competition in search results. Other common meta tags include viewport (critical for mobile responsiveness), charset (defines character encoding, usually UTF-8), and Open Graph tags for social media previews. Older tags like meta keywords are ignored by Google and waste crawl budget if overused. At Ottawa SEO, we audit meta tags across our 500+ domain portfolio monthly. Common mistakes we fix: duplicate title tags across pages, missing or identical meta descriptions (Google will generate its own, often poorly), and forgetting canonical tags on paginated content. We also strip out deprecated tags that bloat the <head> and slow parsing. One tradeoff: meta descriptions don't guarantee Google will use them. Google rewrites roughly 60–70% of descriptions based on query context. Still worth writing them—it's your chance to control messaging when Google does use them, and it forces you to clarify each page's purpose. Write for humans first, then check that your primary keyword appears naturally in both title and description.