HTML5 is a marked switch from its predecessors. Instead of concerning itself with markup identifying the structure of the data, HTML5 is a semantic language focused on markup that provides meaning to the content.
In addition to these semantic tags, HTML5 introduces native support for embedded video and audio, browser-local database storage, a drawing canvas, form controls, WebSockets, and enough other features to fill an entire book—several actually. With new features, HTML5 also reduces the amount of markup we have to write to generate a standards-compliant document.
There's certainly more to HTML5 than we can cover in a single chapter, so we'll focus on the features most important to our application at this time: markup changes, semantic tags, custom data attributes, and the new form controls. We will also introduce the local storage and geolocation services provided by HTML5, as they can be used to greatly enhance the experience of mobile apps.