Which strategy allows you to version a single resource representation in an API?

Content negotiation is a strategy used in APIs to allow clients and servers to communicate and agree upon the representation of a resource. In this context, it enables the API to support multiple versions of a resource without changing the URL structure. Instead of relying on different endpoints or subdomains, content negotiation allows the API server to determine which format or version of the resource to send back based on the client's request headers.

By using content negotiation, clients can request a specific version of a resource by including an Accept header in their HTTP request that indicates the desired representation, which might include different data formats (like JSON or XML) or API versions. This approach provides flexibility and keeps the API cleaner, as it avoids the creation of multiple separate URIs for each version of the resource.

Other strategies, such as URI path versioning or subdomain versioning, tend to require more changes in the URL structure, which can lead to URL proliferation and maintenance challenges. Custom headers, while useful for other purposes, are less standard for indicating basic resource versions. Content negotiation streamlines this process and allows developers to manage versioning of a single resource representation effectively and intuitively.