Previous changes to HTML were by and large pretty small. HTML5 on the other hand is a huge rollout. There are a lot of changes to both advanced and basic features. In HTML5, the core of the basic mark-up language itself has some important changes.
In HTML4, many elements were replaced by new elements. For example, the tag was replaced by the tag. That said, however, the old tags were still supported.
In the new HTML5, old tags won’t be supported at all. That means that although browsers will still be able to display tags, the tags themselves won’t be guaranteed to look the way you want them to.
These are some of the most important changes to the basic mark-up language.
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