UTM parameters are short snippets of code appended to URLs that allow analytics platforms like GA4 to identify exactly where traffic is coming from. The five standard parameters are source (e.g., google), medium (e.g., email), campaign (e.g., spring_promo), term (keyword), and content (ad variant). Consistent UTM tagging across all marketing campaigns enables accurate attribution and prevents traffic from being misclassified as direct or organic.