According to a statement by the company on Tuesday,
Firefox is one of the only browsers to offer any support for Windows XP and Vista.After April 2017, users can still browse with Mozilla Firefox on XP and Vista albeit with an outdated version of the browser.
"Microsoft itself ended support for Windows XP in 2014 and will end support for Windows Vista in 2017. Unsupported operating systems receive no security updates, have known exploits, and can be dangerous to use, which makes it difficult to maintain Firefox on those versions. Firefox security updates for XP and Vista users will continue until September 2017, although new features will not be offered."