Meta tags affect SEO, but their impact varies dramatically by type. Title tags remain one of the top three ranking factors—Google uses them to understand page topics and they directly influence click-through rates from search results. Meta descriptions don't affect rankings directly, but a well-written one can improve CTR by 20-30%, which sends positive user signals back to Google. Meta keywords died around 2009 and carry zero weight with any major search engine. The tags that matter most: Title tags should be 50-60 characters with your primary keyword near the front. Meta descriptions work best at 140-155 characters—longer gets truncated on mobile. The robots meta tag controls indexing and crawling (noindex, nofollow), which is critical when you're managing duplicate content or staging environments. Canonical tags prevent duplicate content issues across your domain, especially important if you run ecommerce with filtered URLs or paginated content. Open Graph and Twitter Card tags don't affect rankings but control how your content appears when shared, which indirectly drives traffic. Viewport and charset tags are technically meta tags but fall into technical SEO—they're table stakes for mobile-first indexing, not ranking boosters. At Ottawa SEO, we see clients who neglect basic title tag optimization while obsessing over schema markup. That's backwards. Fix your titles and descriptions first because they're visible in search results and affect whether users click. One watch-out: Google rewrites title tags in search results about 60% of the time now, especially if yours is keyword-stuffed or doesn't match user intent. They pull from H1s, page content, or anchor text pointing to your page. Meta descriptions get rewritten even more often based on the specific query. That doesn't mean you skip writing them—you're setting the default, and Google still uses your title tag for ranking signals even when they rewrite the display version. Bottom line: prioritize title tags and meta descriptions for every page, use robots and canonical strategically, ignore meta keywords completely.