Mozilla Firefox 42 is a web browser developed by Mozilla Foundation , available for download in full install version for Windows platforms from legacy sources. This version of Firefox was officially released on 2015-11-03 for public access and a brief summary of important updates and change log pertaining to this edition can be read below.

Firefox 42 was released with changes in User Interface, HTML5 element support in addition to known security fixes and performance improvement coding. 

In the user interface improvement area Login manager has noticeable change like Improved heuristics for saving usernames/passwords, copy/paste usernames in the context menu and migration of existing usernames from cross browsers like Chrome, Internet explorer etc. Now with a just single click, an indicator will be displayed in the tab stating the mute of volume while playing media plugins.

From the privacy point, users can block those web elements which record their behavior using Tracking protection. Control center can be used for managing security & privacy options. 

In the HTML5 elements updations front Media Source Extension is included for HTML videos in addition to implementing ES6 Reflect and ImageBitmap.