For the past few years, I have been teaching people the importance of using CSS for layout of web pages and why you shouldn't use tables for layout. But HTML5 changes that. HTML5 recognizes that while tables are not a good layout tool, many designers use them all the time. So, rather than making tables for layout invalid HTML, HTML5 allows them, but recommends that you use a feature that indicates to the user agent that the table is for layout rather than tabular data.
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