The document discusses why HREFLANG tags are not working as intended on a website. It describes a scenario where an e-commerce site targeting the UK and two other countries was having non-UK pages rank for UK search terms. After troubleshooting, the issue was found to be third-party tracking scripts invalidating the HREFLANG tags by placing content in the <head> that only <link>, <style>, and <meta> tags can contain. Moving the <noscript> tag containing tracking pixel code to the <body> resolved the problem.