The Universal Event Tracking (UET) tag is a tracking code provided by Microsoft Bing Ads that you add to your website. It tracks user activity, such as page views, purchases, or sign-ups, and provides insights into how visitors interact with your site. The UET tag is essential for enabling advanced features like conversion tracking, remarketing, and audience creation. By understanding user behavior, you can optimize your campaigns, refine targeting, and calculate the true ROI of your Bing Ads campaigns. Proper implementation of the UET tag is a crucial step for data-driven campaign management.