When creating an accessible website it is essential that you use proper HTML to allow all web browsing software the best chance to correctly read and display your website pages.

The Search Engine Optimization (SEO) advantage of this is that the same rules apply to search engine robots, like googlebot, that scour your website as they index it to their listings.

If the bot is unable to correctly read the HTML then this may result in it hitting a dead end and will prevent it from listing the full web page correctly and may also prevent further pages within your website from being found by the search engine.

Use html elements to give content meaning (semantic markup). As with all programming and markup languages, there are correct and incorrect ways to structure a document. You should stick to standard HTML elements for your markup.

Search engines weigh how relevant your web page is for certain search terms by using these tags.

Correctly including your targeted search terms and thinking about your content and how it fits within your HTML tags can help your web page rank, better than they would without using the tags.