The PHP language evolved without a written formal specification or standard until 2014, with the original implementation acting as the de facto standard which other implementations aimed to follow. Since 2014, work has gone on to create a formal PHP specification. As of September 2019, over 60% of sites on the web using PHP are still on discontinued/EOLed version 5.6 or older;[14] versions prior to 7.1 are no longer officially supported by The PHP Development Team, but security support is provided by third parties, such as Debian. ©