Adobe Flash is gradually being replaced by new technologies on web browsers such as HTML5. Mozilla has joined Google Chrome, Safari and Microsoft Edge in the battle against Flash by blocking Flash elements which are not necessary to the experience of users on the web.
Chrome is still using the ad support of Flash but will turn it off by default when the occasions shows. On the other hand Microsoft developped it own technology "Silverlight".
Adobe Flash is getting old and is subject to repeated problems such as security exploitation, instability, memory leackages impacting the battery and regression in performances. Mozilla says that the transition will lead to a reduction of 10% in crashes or blockages in Firefox also leading to enhanced security, faster page load, better responsiveness and improved battery life.
Mozilla said to still continue supporting silverlight and Flash till 2018 in order to give enough time for enterprises to turn to HTML. They also said that they will first get users consent before a website can activate Flash. You may theredore see some buttons on certain websites that will allow you to display Flash contents
Mozilla is also encouraging websites using Flash o Silverlight to turn to HTML for videos and online games. Finally, Mozilla is still testing new features that will help improve Firefox in the fields of collaboration and discovery.