Firefox 57.0 64-bit

New:
A completely new browsing engine, designed to take full advantage of the processing power in modern devices.
A redesigned interface with a clean, modern appearance, consistent visual elements, and optimizations for touch screens.
A unified address and search bar. New installs will see this unified bar. Learn how to add the stand-alone search bar to the toolbar.
A revamped new tab page that includes top visited sites, recently visited pages, and recommendations from Pocket (in the US, Canada, and Germany)
An updated product tour to orient new and returning Firefox users.
Video decoding is shut down when the tab playing the media is sent to the background or the video is not visible on the screen. Video resumes when the media tab is in the foreground and the player is visible on the screen. Audio will not be affected.
AMD VP9 hardware video decoder support for improved video playback with lower power consumption.
An expanded section in preferences to manage all website permissions.

Fixed:
Various security fixes.

Changed:
Firefox now exclusively supports extensions built using the WebExtension API, and unsupported legacy extensions will no longer work. Learn more about our efforts to improve the performance and security of extensions.
The browser's autoscroll feature, as well as scrolling by keyboard input and touch-dragging of scrollbars, now use asynchronous scrolling. These scrolling methods are now similar to other input methods like mousewheel, and provide a smoother scrolling experience.
The content process now has a stricter security sandbox that blocks filesystem reading and writing on Linux, similar to the protections for Windows and macOS that shipped in Firefox 56.
Middle mouse paste in the content area no longer navigates to URLs by default on Unix systems.
Removed the toolbar Share button. If you relied on this feature, you can install the Share Backported extension instead.
Some older versions of the ATOK IME, including ATOK 2006, 2008, 2009 and 2010, can cause crashes and are therefore disabled on the Windows 64-bit version of Firefox Quantum. To fix those incompatibility issues, please use a newer version of ATOK or one of other IMEs.
The default font for Japanese text is now Meiryo.