Android is a Linux-based operating system that Google offers as open source under the Apache license. It is designed primarily for mobile devices such as smartphones and tablet computers. Android supports low-cost ARM systems and others. The first tablets running Android were released in 2009. Vendors such as Motorola and Lenovo delayed deployment of their tablets until after 2011, when Android was reworked to include more tablet features. Android 3.0 (Honeycomb), released in 2011 and later versions support larger screen sizes, mainly tablets, and have access to the Google Play service. Android includes operating system, middleware and key applications. Other vendors sell customized Android tablets, such as Kindle Fire and Nook, which are used to consume mobile content and provide their own app store, rather than using the larger Google Play system, thereby fragmenting the Android market.