What is HTML5 ?

Support all existing web pages; no requirement to go back and revise older websites
Reduce the need for external plugins and scripts to show website content
Improve the semantic definition (i.e. meaning and purpose) of page elements
Make the rendering of web content universal and independent of the device being used
Handle web documents errors in a better and more consistent fashion

Note

Navigation is a core part of accessibility, and screen readers rely on you to provide the structure of your page. This is accomplished with semantic HTML elements.
To increase the page accessibility, the role attribute can be used to indicate the purpose behind an element on the page to assistive technologies. The role attribute is a part of the Web Accessibility Initiative (WAI), and accepts preset values.
Every region role requires a label, which helps screen reader users understand the purpose of the region. One method for adding a label is to add a heading element inside the region and then reference it with the aria-labelledby attribute.
It is important to link each input to the corresponding label element. This provides assistive technology users with a visual reference to the input. This is done by giving the label a for attribute, which contains the id of the input.
Although not required for label elements with a nested input, it is still best-practice to explicitly link a label with its corresponding input element.
The footer element is a container for a collection of content that is related to the page, and the address element is a container for contact information for the author of the page.
The address element does not have to contain a physical geographical location. It can be used to provide a link to the subject.

[!Knowledge] HTML elements reference Wrap with abbreviations Remove Tag