Content negotiation enables the Web API to return different representations of the same resource based on the client's preferences and capabilities. In ASP.NET Core, you can implement content negotiation by using the Accept header or query parameters to specify the desired response format, such as JSON, XML, or others. The framework automatically selects the appropriate formatter based on the client's preference or the default configuration. Additionally, you can use the Produces attribute to specify the supported response formats for each action or controller. Content negotiation allows clients to consume the API in their preferred format.