On a website, third-party resources are typically defined as any resources (such as scripts, stylesheets, or images) that are loaded from a domain that is different from the primary domain of the website. In other words, these are resources that are hosted by a third-party service or provider, rather than on the website's own server.

Examples of third-party resources include ads from ad networks, social media widgets, Google Analytics scripts, and embedded videos from services like YouTube or Vimeo.

In contrast, primary resources are resources that are loaded directly from the website's own domain or server, such as the website's HTML, CSS, and JavaScript files, images, and other media assets.

Third-party resources can be useful for adding additional functionality or content to a website, but they can also affect the website's performance and user experience, as they can add additional latency and increase the number of network requests required to load the page.

Learn more about how third party resources are optimised by different parts of the technology stack across hosting, content delivery networks, and providers like Chinafy.