An ETag, or entity tag, is an HTTP header that serves as a unique identifier for a specific version of a resource. It’s like a fingerprint for a particular resource, ensuring that the client (e.g., a web browser) has the most up-to-date version. ETags are crucial for efficient web caching, allowing clients to avoid downloading unchanged resources.
ETags not only enhance the user experience by reducing load times but also save bandwidth and server resources. They contribute to a more efficient and performant web, especially for frequently accessed resources like images, CSS, and JavaScript files. Understanding how to buy an ETag plays a vital role in optimizing web performance and delivering a seamless browsing experience for users.