The long awaited HTML5 standard has now been published. HTML5 has adopted some of the many recommendations for moving away from insecure technologies.
HTML5 is designed for a rich text format web document. HTML5 includes detailed processing models to encourage more interoperable implementations; it extends, improves, and rationalizes the markup available for documents and introduces markup and application programming interfaces (APIs) for complex web applications. For the same reasons, HTML5 is also a candidate for cross-platform mobile applications because it includes features designed with low-powered devices in mind.
Many new syntactic features are included. <audio> <video> <canvas> are some of the new containers. Additional formatting includes <main>, <section>, <article>, <header>, <footer>, <aside>, <nav> and <figure>.
WordPress has indicated that migration to HTML5 should be completed in short order. Themes and plugins also have to be modernized which probably take more time. The improved HTML5 should make WordPress much more efficient.