It’s a major new version number, but there’s not much to get excited about in Firefox 56.0, unless the ability to take screenshots in your browser was on your wish list.
Also new in Firefox 56.0 is the Send Tabs feature, which allows you to send web page links to your other devices. Right click on any web page and select Send Page To Device to try it. I suppose it’s easier than sending yourself email.
Starting with version 56.0, Firefox’s web form autofill feature can fill in address fields. I didn’t even know this was missing in previous versions. In any case, this feature is currently only available for users in the USA; it will be made available in other countries in the coming weeks.
Firefox’s preferences (Options) pages have been reorganized and cleaned up significantly. There’s now a search box on the Options page, which should make finding that elusive setting a bit easier. The explanatory text associated with many options has been improved for clarity. The privacy options and data collection choices have been reworked so they are better aligned with the updated Privacy Notice and data collection strategy.
Finally, media on background tabs will no longer play automatically; it will only start playing once the associated tab is selected.
The release notes for Firefox 56.0 have additional details.