Apple today (July 25, 2012) announced that OS X Mountain Lion, the ninth major release of the world’s most advanced desktop operating system, is available as a download from the Mac App Store. With more than 200 innovative new features, Mountain Lion includes iCloud integration, the all new Messages app, Notification Center, system-wide. At that point, Mac users using OS X 10.6 Snow Leopard, 10.7 Lion, and 10.8 Mountain Lion will be left behind by the current versions of Firefox. It will be a sad day, as Firefox is the last major browser to support Mac OS X 10.6 through 10.8.
Starting with Firefox version 49, Firefox requires Mac OS X 10.9 (Mavericks) or higher. Visit this Apple Support page to find your Mac OS version.
Best Browser For Mac Os X Lion
If you're using an outdated version of Firefox on Mac OS X 10.8 (Mountain Lion) or earlier, the only way you can update Firefox to a secure version is to upgrade your Mac OS to a version that Apple supports. Visit this Apple Support page to learn more about upgrading your Mac.
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Firefox For Mac Os X Lion 10.7.5
While insecure versions of Firefox will continue to work on OS X 10.8 and earlier, using an up-to-date version of Firefox on a supported version of Mac OS will provide you with the best and safest user experience.