Essential cookies, also known as strictly necessary cookies, are files required for a website to function correctly. They enable core functionalities like user authentication, site navigation, and processing online transactions (e.g., a shopping cart). Disabling them can impair a website's security, accessibility, and performance. 

Analytics cookies, or performance cookies, are used to monitor user behavior on a website to help owners understand traffic and improve site performance. They anonymously collect data like the number of visitors, which pages they visit, how long they stay, and how they arrived at the site. Websites use this information to analyze user trends and make data-driven decisions to enhance user experience. 

Advertising cookies are small data files that track user behavior on and across websites to show personalized ads. They collect information such as browsing history, location, and device type to build a profile of interests and deliver relevant advertisements, though some cookies used for ad measurement are not used for personalization.