What's the key difference between HTML 4 and HTML 5?

Question

What are the key differences between HTML4 and HTML5 draft?

Please keep the answers related to changed syntax and added/removed html elements.

Answer 1

You'll want to check here for the complete diff. But there are many new elements and element attributes. Some elements were removed and others have different semantic value than before. There are also APIs defined, such as the use of canvas, to help build the next generation of web apps and make sure implementations are standardized.

Answer 2

From Wikipedia:

• New parsing rules oriented towards flexible parsing and compatibility
• New elements – section, video, progress, nav, meter, time, aside, canvas
• New input attributes – dates and times, email, url
• New attributes – ping, charset, async
• Global attributes (that can be applied for every element) – id, tabindex, repeat
• Deprecated elements dropped – center, font, strike

Answer 3

HTML 5 invites you give add a lot of semantic value to your code. What's more, there are natives solution to embed multimedia content.

The rest is important, but it's more technical sugar that will save you from doing the same stuff with a client programming language.

Answer 4

HTML5 has several goals which differentiate it from HTML4.

The primary one is consistent, defined error handling. As you know, HTML purposely supports 'tag soup', or the ability to write malformed code and have it corrected into a valid document. The problem is that the rules for doing this aren't written down anywhere. When a new browser vendor wants to enter the market, they just have to test malformed documents in various browsers (especially IE) and reverse-engineer their error handling. If they don't, then many pages won't display correctly (estimates place roughly 90% of pages on the net as being at least somewhat malformed).

So, HTML5 is attempting to discover and codify this error handling, so that browser developers can all standardize and greatly reduce the time and money required to display things consistently. As well, long in the future after HTML has died as a document format, historians may still want to read our documents, and having a completely defined parsing algorithm will greatly aid this.

The secondary goal of HTML5 is to develop the ability of the browser to be an application platform, via HTML, CSS, and Javascript. Many elements have been added directly to the language that are currently (in HTML4) Flash or JS-based hacks, such as <canvas>, <video>, and <audio>. Useful things such as Local Storage (a js-accessible browser-builtin sql database, for storing information beyond what cookies can hold), new input types such as date for which the browser can expose easy user interface (so that we don't have to use our js-based calendar date-pickers), and browser-supported form validation will make developing web applications much simpler for the developers, and make them much faster for the users (since many things will be supported natively, rather than hacked in via javascript).

There are many other smaller efforts taking place in HTML5, such as better-defined semantic roles for existing elements (<strong> and <em> now actually mean something different, and even <b> and <i> have vague semantics that should work well when parsing legacy documents) and adding new elements with useful semantics - <article>, <section>, <header>, <aside>, and <nav> should replace the majority of <div>s used on a web page, making your pages a bit more semantic, but more importantly, easier to read. No more painful scanning to see just what that random </div> is closing - instead you'll have an obvious </header>, or </article>, making the structure of your document much more intuitive.

Answer 5

You might be interested in this list of HTML5 elements and attributes.

Also, please note that it's "HTML 4", not "HTML4". Indeed, for HTML 5, both variants are used, but there is an important difference in meaning. HTML 5 refers to the name of the W3C specification, whereas "HTML5" is the document type of those HTML files with a text/html MIME type that follow this spec. The same goes for XHTML 5 vs. XHTML5.