From a broader PERSPECTIVE, HTML was a simple language for LAYING out text and images on a webpage, whereas HTML5 can be viewed as an application development platform that does what HTML does that and more, INCLUDING better support for audio, video, and interactive graphics.

It has a number of new elements, supports offline data storage for applications, and has more robust exchange protocols. Thus, proprietary plug-in technologies LIKE Adobe FLASH, Microsoft Silverlight, Apache Pivot, and Sun JavaFX are no longer needed, because browsers can now process these elements without additional requirements.

From a broader perspective, HTML was a simple language for laying out text and images on a webpage, whereas HTML5 can be viewed as an application development platform that does what HTML does that and more, including better support for audio, video, and interactive graphics.

It has a number of new elements, supports offline data storage for applications, and has more robust exchange protocols. Thus, proprietary plug-in technologies like Adobe Flash, Microsoft Silverlight, Apache Pivot, and Sun JavaFX are no longer needed, because browsers can now process these elements without additional requirements.