Enter HTML 5. HTML 5 is a collection of new features for HTML that aim to better cater for the needs of today’s web. For example, videos can be embedded directly into a page (currently youtube and the like use flash), and the new canvas tag will allow a range of graphical effects to be achieved much more easily than today. Changes such this will aid developers, as well as making the web more widely accessible – fewer plugins and third party applications will be needed. New tags allows us to more accurately describe content – new tags such has header, footer and article give more specificity to markup, which should allow search engines to better index content and assists alternative browsers (screen readers for example) as well.
A key issue with any new technologies is backwards computability. The whole world won’t suddenly download a new browser so that we can all use HTML5 on our websites. HTML 5 aims to offer backwards compatibility wherever possible, so we can start using it sooner rather than later and still have the site work in older browsers – a refreshing change from the normal way of things on the web.
Some of the components of HTML5 are already supported by latest browser versions, and others will follow shortly. If you want to find out more about HTML 5, this wikipedia article is a good staring point.