HTML 5 is the next version of hypertext markup language that is currently used to code static web pages today. What is great about the new version is that it may fundamentally change how we see the web and how we interact with applications. With HTML 5 more and more applications can be embedded right into web pages. The new markup language will do away with many complexities of the old one and introduce new tags like <video>, <audio> to embed video and audio respectively.
HTML 5 is getting industry-wide support from all biggies like Google, Mozilla, Apple and more. In fact, the latest web browsers by these companies support HTML 5. The biggest and visible impact of this technology may be the diminishing use of flash videos that are currently used heavily on video sites like YouTube. Some also predict that gradually with the increasing use of the new markup language, even current OS may take a back seat as more and more applications will rely on cloud computing and will run within browser.
But HTML 5 does not have a smooth road ahead. For one, this is still a evolving standard and may continue to be so in the coming years. Moreover, it has not got much support from Microsoft as its current browser IE 8 does not support this markup while Safari 4, Chrome and Firefox 3.5 do. The there is an issue of backward compatibility. The much hyped <video> tag supported by the latest browsers is not supported in their earlier versions.
HTML 5 is promising in terms of bringing more cohesiveness to users' experience on the web and desktop and will certainly revolutionize the way we see software but it has to tackle some roadblocks first. You can see the HTML 5 tags in action at youtube.com/html5. But remember you got to have the latest versions of aforementioned browsers to watch videos.