Question

What can it do? and what can’t it do? (in relation to flash)

Answer 1

HTML5 doesn’t do anything, per se. It’s a spec; one that isn’t finished yet. Sure, many of its proposed features will allow developers to produce similar features as Flash, but it’s up to the browser developers to implement said specification. Currently, there’s a good amount of its proposed spec implemented in different ways by different browser vendors. If your application only uses something that supports some of the HTML5 spec (webkit-based Safari 5/Chrome/Chromium for instance), you can do a lot (ahem, guessing your question stems from Steve Jobs mentioning HTML5 in a Keynote™)…but will struggle with cross-platform support. Many of the major players in the browser market haven’t even agreed on a common codec for video yet (H.264 for many, not supported currently by Firefox/Opera/etc. which use ogg/theora) so basically we’re going back to pre-flash days of plugin-madness for a bit.

Some of the exciting features proposed in the spec for me are:

• flexible canvas for scripting drawings, images, animations
• more semantically accurate documents
• custom data attributes
• video and audio support (assuming something is agreed upon with RE: to codecs)
• web/browser database

One of the major things that I personally would find to be a pain to produce using the proposed HTML5 spec:

• animation and design. Ok, this is a coding site, but I’m a designer who codes and I work with a lot of designers. I don’t want to have to programmatically animate a vector walkcycle 😀 …canvas has little to no support for designers..do you see your designer friend writing code like this?)

Here’s an app that shows a little bit of HTML5: http://9elements.com/io/projects/html5/canvas/

You’ll note that it may “run up” your processor a bit (hey, just like flash!).

In the next 5-10 years it’ll all be possible. Most of the spec is (if at all) partially supported in major browsers. You can keep up with which major browser’s layout engines support what here. Officially though, the spec is scheduled to be complete in 2012, and recommended by 2022. Flash will still be a major player for a bit.

http://html5gallery.com/

and just in case:

http://ishtml5readyyet.com/

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Edit just to add a few more notes from a blog comment I posted recently

HTML5 is about semantics and interoperability; it defines a recommendation about how HTML producers should produce documents. If browsers adopt these standards, it will make it easier for producers to create interoperable content that can be consumed sans plugin.
This is why I love Flash; because it’s standards are implemented by the same people who “wrote” the standards. It behaves the same cross-platform (mostly) because it’s a plugin. The primary intention of HTML5 is to reduce the need for plugins.

One thing we (we being developers, designers) need to be careful with is lumping CSS3 and Javascript in with HTML5. Much of the cool stuff you see that is denoted as HTML5, isn’t (Apple’s recent “HTML5” showcase–which, the majority of which was not HTML5–is a great example). It’s jQuery; it’s CSS3 animations and transformations; it’s proprietary video codecs that are only supported it one browser. Much to my chagrin, HTML5 has become the new “Web 2.0”, representing a wide body of somewhat related technologies.