Conversion tracking in Meta ads measures specific actions users take on your website or app after interacting with your Facebook or Instagram campaigns. You install the Meta Pixel (a JavaScript snippet) on your site or integrate the Conversions API (server-side tracking) to capture events like purchases, form submissions, add-to-carts, or phone calls. Meta then attributes these conversions back to the ads that drove them, giving you cost-per-conversion metrics and enabling the algorithm to optimize delivery toward users likely to convert. The system works through cookies and probabilistic matching. When someone clicks your ad, Meta drops a cookie. When that person completes a tracked event within the attribution window (default is 7-day click, 1-day view), Meta registers it as a conversion. You define events in Events Manager, either through standard events (Purchase, Lead, CompleteRegistration) or custom events tailored to your funnel. Each event can pass parameters like value, currency, and content IDs for granular reporting. Without conversion tracking, you're flying blind. You might see 10,000 clicks at $0.80 CPC, but have no idea if those clicks generated $500 or $50,000 in revenue. With tracking, you see that Campaign A drove 47 purchases at $34 cost-per-purchase while Campaign B drove 12 at $89, letting you shift budget intelligently. Meta's algorithm also uses this data for campaign optimization—Conversions campaigns literally cannot work without a conversion event configured. Key technical points: iOS 14.5+ privacy changes now limit tracking windows and require domain verification. The Conversions API has become essential because it sends data server-to-server, bypassing browser restrictions that block the Pixel. At Ottawa SEO, we run both Pixel and CAPI in parallel for maximum signal, especially for e-commerce clients where purchase tracking directly informs ROAS calculations. Expect 15–25% of conversions to go untracked even with perfect setup due to privacy tools and cross-device journeys. Set up Google Analytics 4 alongside Meta for reconciliation, because Meta's attribution will always show rosier numbers than last-click models.