Content Negotiation in Web API
jQuery) by default the data is returned in JSON format. However, in
certain cases you lay want to retrieve the data in XML format instead of
JSON. On the server side, Web API determinses what data format to use
for sending data to the client by doing what is known as Content
Negotiation. Simply put, content negotiation is a process by which Web
API inspects the incoming request and HTTP headers accompanying the
request to figure out what response format(s) the client can understand.
Based on this checking Web API sends the output.