This document discusses different approaches for building real-time web functionality and introduces SignalR as a solution. It describes how earlier approaches like periodic pooling and long polling have disadvantages. Web sockets are ideal but have limitations in support across browsers, proxies, and web servers. SignalR abstracts these transports to provide a simple and robust library for adding real-time functionality to ASP.NET applications without these constraints. The document demonstrates SignalR and provides resources to learn more.