A tracking pixel — also called a web beacon or 1x1 pixel — is a tiny, invisible image embedded in a webpage or email that transmits data to a server when loaded. Unlike browser-stored cookies, it triggers an HTTP request sending the user's IP address, browser type, device, and page viewed. Tracking pixels are used by advertising platforms (Meta Pixel, Google Ads) and email tools to track opens and conversions. Under the ePrivacy Directive, pixels that process personal data require prior consent, the same standard as cookies. European regulators including the CNIL have fined sites that load pixels before consent is given.