Is there a way to create your own html tag in HTML5?

I'm not so sure about these answers. As I've just read: "CUSTOM TAGS HAVE ALWAYS BEEN ALLOWED IN HTML."

http://www.crockford.com/html/

The point here being, that HTML was based on SGML. Unlike XML with its doctypes and schemas, HTML does not become invalid if a browser doesn't know a tag or two. Think of <marquee>. This has not been in the official standard. So while using it made your HTML page "officially unapproved", it didn't break the page either.

Then there is <keygen>, which was Netscape-specific, forgotten in HTML4 and rediscovered and now specified in HTML5. And also we have custom tag attributes now, like data-XyZzz="..." allowed on all HTML5 tags.

So, while you shouldn't invent a whole custom unspecified markup salad of your own, it's not exactly forbidden to have custom tags in HTML. That is however, unless you want to send it with an +xml Content-Type or embed other XML namespaces, like SVG or MathML. This applies only to SGML-confined HTML.

You can use custom tags in browsers, although they won’t be HTML5 (see Are custom elements valid HTML5? and the HTML5 spec).

Let's assume you want to use a custom tag element called <stack>. Here's what you should do...

STEP 1

Normalize its attributes in your CSS Stylesheet (think css reset) - Example:

 stack{display:block;margin:0;padding:0;border:0; ... }

STEP 2

To get it to work in old versions of Internet Explorer, you need to append this script to the head (Important if you need it to work in older versions of IE!):

 <!--[if lt IE 9]> 
 <script> document.createElement("stack"); </script>
 <![endif]-->

---

Then you can use your custom tag freely.

<stack>Overflow</stack>

Feel free to set attributes as well...

<stack id="st2" class="nice"> hello </stack>