YouTube was built around Adobe's Flash Player. Over the past few years, YouTube (and parent company Google) has been moving away from Flash.
Besides being filled to the brim with security holes, Flash Player is an inconvenient add-on to most Web browsers. YouTube will now stream videos through HTML5.
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For those who aren't familiar with programming, HTML is the building block for almost every website. HTML5 added media and interactive features to the programming language.
Besides being more secure than Flash Player, HTML5 also allows YouTube to improve video quality and streaming speed for its content.
YouTube engineering manager Richard Leider explained why HTML5 was so valuable to YouTube in his announcement:
Combined with Common Encryption, we can support multiple content protection technologies on different platforms with a single set of assets, making YouTube play faster and smoother.
The most important feature that HTML5 will bring to YouTube is Google's VP9 video codec. Google claims that VP9 helps videos start 15 to 80% faster than other video codecs.
This isn't newfangled tech either, VP9 has been tested and used on other sites since 2013.
Want to test out Google's new HTML5 format? Click here to find out where to see official NFL highlights on YouTube.