What is Content Negotiation?

Content negotiation allows serving different representations of the same resource based on client capabilities and preferences. The Accept header specifies preferred media types (application/json, text/html). Accept-Language indicates language preference (en, de, fr). Accept-Encoding specifies compression support (gzip, br). The server examines these headers and responds with the best match, indicating the choice via Content-Type, Content-Language, and Content-Encoding response headers. This enables APIs to return JSON or XML from the same endpoint, serve WebP images to supporting browsers with JPEG fallback, and deliver localized content — all at the same URL.