Flash has been on its way out for a very long time. Now Google Chrome is to replace Flash with HTML5 in its 55th version.
The Adobe Flash Player is needed to play videos and other animations on the Internet. In many browsers if you want to watch YouTube videos, you need the Adobe Flash player add-on. But many browsers are replacing Adobe Flash player with HTML5 which can also play online videos straightaway.
Most of the browsers are doing away with Adobe Flash Player because it is very resource hungry and there are also prospects of security vulnerability. Another problem is, if your browser relies on Adobe Flash Player in order to display videos, without the plug-in, you are stuck. HTML5 on the other hand can run videos and graphics without needing a plug-in. Just as you can embed images and graphics into HTML, using HTML5, you can also embed videos.
Websites that heavily use HTML5 instead of Adobe Flash Player not just improve their security, they also reduce power consumption and reduce page load times to a great extent, according to this Google Chrome blog post about the decision to replace Adobe Flash Player with HTML5.
From Google Chrome 55 onwards, HTML5 will be functional by default. If a website requires you to have the Adobe Flash Player plug-in, you will be prompted to install it on your browser.