HTML5 defines several new technologies to both communicate with thehost device as well as allow for web applications to run when there isno Internet connection.These technologies include Local Storage, Web SQL, Application Cache, Session history and navigation, geolocation and canvas. They allow us to build web applications that aren't dependent on a server after being loaded initially. This not only makes offline apps possible, but can make online apps faster. Mobile devices often rely on an Internet connection that can be lowband width, high latency, and unreliable. The typical enhancements of increasing performance by using gzip, minimizing requests, and minifying documents can only go so far. By using client side technologies to improve the responsiveness of our web sites by hiding the effect of slow network requests or a network connection that is temporarily unavailable.This talk explores these new technologies and the strategies that can be used in conjunction with them to create more responsive applications. We will be looking at local caching, local data storage and syncing, and optimistic asynchronous UI updates. We will see what the benefits and pitfalls are with several of these strategies. We will look at some real world applications that have successfully leveraged HTML5.