Humans account for less than 40% of all web traffic. Which means that there are more robot ‘eyes’ watching your website than humans are browsing it, clicking it and touching the web interface you have created.
Why bother about robots and semantic markup?
Practical example: if Google (or any other search engine) cannot read your website correctly it won’t be able to display it in its search results. When Facebook cannot find the correct image to show next to your link on Facebook it will just take the first alternative it can find.
So if you want to be 100% sure how things are being displayed (or are displayed at all), make sure to use the correct (semantic) mark up.
You got visual
Of course you are surfing the trend of the visual web and you are making sure your website is an absolute visual tastemaker. You are working your h1 tags for SEO, however what about the rest of your markup? Have you considered that the average non human visitor on your website won’t notice that something is an address because of the lack of semantic markup? The bot might see the term ‘address’ caught within h2 tags, though it doesn’t know what in the next couple of lines is the address. So how do you make sure your non-human visitors will find the address you want them to find.
Don’t start worrying now, you don’t have choose between your nice visual style and semantic markup. It is about how you can use semantic markup together with your visual style to give your web page the right structure for robots to understand.
Pick your semantic markup
To right type of semantic depends on the robots visiting your site. So besides your human audiences, which of your robot audiences do you like to serve, since there are many different types of self-proclaimed standards (schema.org, microformats, opencyc etc) for in page optimisation of semantic mark up.
Schema.org is the one that is supported by Google, Microsoft, Yahoo! and Yandex, which could therefore be your semantic mark up basis of choice if you mainly target search engines and want to use their unique functionalities to display and list certain content.
The big benefit doing it right
If you do your semantics right you are not only controlling how your website is being displayed in general, but also how and what is displayed by other services that use a robot to visit your site and digest your content.