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

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 2

You'll want to check HTML5 Differences from HTML4: W3C Working Group Note 9 December 2014 for the complete differences. 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.