HTML 5 is an ongoing effort to update and improve the HTML standard. It introduces several new capabilities including offline database storage, 2D graphics animations using <canvas>, and embedding audio and video content. While still a work in progress, HTML 5 features are starting to be supported by all major browsers like Opera, Safari, Internet Explorer, and Firefox. The specification defines new elements, attributes, and events, and provides more precise rules for how HTML elements should be handled and errors recovered from.