This document discusses WCF Web API, which allows developers to expose applications, data, and services over HTTP. It provides an overview of WCF Web API, explaining that it handles low-level HTTP details and exposes an HTTP programming model. The document also notes that WCF Web API supports many client and device types, and is important for reaching users on their devices. It outlines the architecture of building a web API for browser and JSON clients with WCF Web API.