Mozilla seems determined to keep us guessing with new versions of Firefox. New versions that are not assigned a major new version number (e.g. 41, 42) are not announced in any way. When a new version is (apparently arbitrarily) assigned a major new version number, Mozilla publishes a post on the Mozilla blog. This post never includes any mention of the new version identifier, and typically doesn’t even say that there’s a new version.

For example, the post associated with Firefox 42 says this: “We’re releasing a powerful new feature in Firefox Private Browsing called Tracking Protection” and “We hope you enjoy the new Firefox!” What new version? When will it be released? We’re left guessing the answers to these rather obvious questions.

According to the release notes for Firefox 42, it was released on November 3. The Mozilla blog post describes changes to Firefox’s Private Browsing mode, including the new Tracking Protection, which “actively blocks content like ads, analytics trackers and social share buttons that may record your behavior without your knowledge across sites.”

Firefox 42 adds a small speaker icon that appears next to the caption for any tab that’s currently playing audio. You can mute a tab’s audio by clicking the speaker icon. The Login Manager has been improved in several ways. Performance has also been beefed up for sites that perform a lot of restyling. HTML5 support was improved.

Firefox 42 includes fixes for at least eighteen security bugs, according to the Security Advisories page. Recommendation: update Firefox to version 42 as soon as possible.