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iOS
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<p>iOS (formerly iPhone OS) is a <a href="/facts/Mobile_operating_system/wysBVca1">mobile operating system</a> created and developed by <a href="/facts/Apple_Inc./oTJYta3k">Apple</a> for its <a href="/facts/IPhone/h5WeKRl9">iPhone</a> line of smartphones. It was unveiled in January 2007 alongside the <a href="/facts/IPhone_(1st_generation)/xwVatAHK">first-generation iPhone</a>, and was released in June 2007. <a href="/facts/IOS_version_history/4CILLmV7">Major versions of iOS</a> are released annually; the current stable version, <a href="/facts/IOS_18/rGqpQMcS">iOS 18</a>, was released to the public on September 16, 2024. </p><p>Besides powering iPhone, iOS is the basis for three other <a href="/facts/List_of_Apple_operating_systems/mrqrldMc">operating systems made by Apple</a>: <a href="/facts/IPadOS/fClrmH7D">iPadOS</a>, <a href="/facts/TvOS/jDMqvvfI">tvOS</a>, and <a href="/facts/WatchOS/zH1fkn2R">watchOS</a>. iOS formerly also powered <a href="/facts/IPad/Ql67x0Dw">iPads</a> until iPadOS was introduced in 2019 and the <a href="/facts/IPod_Touch/PRJabx51">iPod Touch</a> line of devices until its discontinuation. iOS is the world's <a href="/facts/Usage_share_of_operating_systems/zcuukwfc">second most widely installed mobile operating system</a>, after <a href="/facts/Android_(operating_system)/nNyHb0xz">Android</a>. As of December 2023, Apple's <a href="/facts/App_Store_(iOS)/0yqcGqey">App Store</a> contains more than 3.8 million iOS <a href="/facts/Mobile_apps/r7vp6meo">mobile apps</a>. </p><p>iOS is based on <a href="/facts/MacOS/Y93vVpTm">macOS</a>. Like macOS, it includes components of the <a href="/facts/Mach_(kernel)/rqK8DES2">Mach</a> microkernel and <a href="/facts/FreeBSD/RKsFTm7F">FreeBSD</a>. It is a <a href="/facts/Unix-like/YAKrAxzd">Unix-like</a> operating system. Although some parts of iOS are open source under the <a href="/facts/Apple_Public_Source_License/sujXlYJA">Apple Public Source License</a> and other licenses, iOS is <a href="/facts/Proprietary_software/9zcskxYL">proprietary software</a>. </p>