We hear so much about "semantic html". Where/what are the algorithms reading our semantic html?

I keep making attempts at properly using HTML5 but I feel like it's still not even close to anything semantically valuable.

My attempts:

• HTML5 Article node Architecture
• HTML5 Blog Page Architecture

But there's such subtleties in every single tag!

My question is, what specific software out there on the web is actually doing things like processing our HTML DOM, calculating and comparing elements to say "oh, this is a <header>, and it's just after <section>, and it has <time> in it, so the <time> tag must be "metadata" in relation to the <header>...", and saying "The content within the <time> tag not only is the "published time", but also relates to the author's birthday, so it must be a special post (say because there was also a <cite> or <address class='vcard'> tag in there too)".

I mean, what benefit am I ever going to get in using HTML5 if I don't know the algorithms that are interpreting it? If I just stuck with the basic div, ol, ul, li, p, a, h[1-6] tags, I could do everything with half the number of DOM elements.

Looking forward to some specific algorithms that I can use to shape how I structure the DOM from here on out.

I'm at the point where I don't even t开发者_JAVA技巧hink we should be using HTML5 tags at all. For example, on the iPhone especially, the goal should be to minimize dom elements to decrease load time. Plus, if the iPhone site is a mirror of the traditional browser version, the search engines won't even see the iPhone site (ideally). So there's no real point in making the DOM semantic. So if I can use 1/2 the amount of <div> tags to achieve the same layout as if I used a somewhat "semantic HTML5" rendition, and that's a good thing for the iPhone, why don't I do that for the regular browser too? That's where I'm coming from.

Articles like this are basically saying it's pointless to worry about semantic HTML.

What algorithms are reading your semantic HTML? Google, that's who. Their algorithm tries to extract every bit of meaning from pages that it can, because that helps Google construct smart, relevant search results. For one example, Google tries to determine the dates of things by reading the HTML and gives headers extra consideration in determining the overall topic of a page.

Also, your assertion that we shouldn't use HTML5 tags on the iPhone "to minimize dom elements" isn't founded in any technical basis. HTML5 doesn't dictate that we use more DOM elements, and in fact it can let us leave out tags that would be required by XHTML. You should use HTML5 on the iPhone more than anywhere else. For example, the new input types like number and email don't do much on the desktop, but that extra information can really make things nicer on the iPhone by allowing it to present an appropriate interface.

Whenever a "machine" tries to make sense of your content.

In addition to search engines (→ SEO), screen readers (→ Accessibility) interpret the markup. They get better from version to version.

Also, think of all the tools that might come one day. The great thing about the Web is, that all the web pages could still exist in 5, 10, 100 … years from now. Imagine the user-agents and algorithms and search tools that might exist then, and how they could extract the meaning of your old documents.

Search engines can/will better interpret your pages which combined with other factors will result in better rankings for your pages.

Moreover if you use the tags consistently and semantically, you could build your own reusable widgets and libraries that derive knowledge from the HTML structure independent of how the data is stored in the backend.

Consider this sample Google search where you can filter results by date. By using semantic HTML, for let's say, <article> and <time>, you can write a simple crawler that recreates this functionality or allows users to specify a timespan within which to search articles in your own site(s).

Off the top of my head, I don’t know of any algorithms making use of the new semantic tags in HTML5. (Obviously, that doesn’t mean there aren’t any.)

But the idea that you should tailor your HTML to specific algorithms is, I think, a bit contrary to how the web works. The web is worldwide, and will hopefully be around for a long time. We can’t know what uses our HTML will be put to, and useful algorithms can’t be written until there’s a good amount of actual content out there.

The <a> tag wasn’t designed with Google’s PageRank algorithm in mind. Some people thought links would be useless if they weren’t inherently two-way, because you’d get too many broken links when one end went away.

Of course, if the vague possibility of undefined future benefits makes it not worth using some or all HTML5 tags for whatever project you’re working on, don’t use them.

For me, the benefit of using them is that there’s a well-known, public, non-proprietary specification that tells you, and anyone else working on the code, what we’ve agreed the tags mean. Future developers don’t just get a <div> with a class name that I made up in a coffee-fuelled 7 p.m. code print, they get a tag designed and documented by people smarter and more experienced than me. There’s also the chance that the code will become more useful in future if people use the meaning contained in HTML5 tags in algorithms, whereas there’s less chance of that if it’s all just a bunch of <div>s.

I don’t think the size increase of our pages from HTML5 tags is particularly worth worrying about though. After gzipping, the size increases aren’t enough to worry about, especially as mobile performance is as much hampered by the latency (which you can’t do much about) as the bandwidth. Plus mobile bandwidth is likely to trend up, rather than down.