As interest in "Web APIs" continues to rise, it’s important to know the advantages and downsides of various implementation strategies. The most common style for “Web APIs” today is based on identifying entities using URIs and applying CRUD operations against those URIs via HTTP methods. In this session, we'll explore an alternate approach to implementing APIs, based on designing messages instead of URIs and using in-message affordances (links and forms) instead of direct protocol methods.This talk provides a working definition for Hypermedia Types, identifies the H-Factors that can appear in any hypermedia type, and the four design elements used in authoring hypermedia types. The talk includes multiple working examples of hypermedia APIs. Additional topics include documenting hypermedia, extending & versioning, and registering designs for wider use on the Web. Along the way, attendees will see illustrations of implementation experience “inthe wild” along with commentary on the inherent costs and potential benefits of adopting a hypermedia style for APIs.