The Open Handset Alliance, a group of more than 30 technology and mobile companies, developed Android: the first complete, open, and free mobile platform. To help developers get started developing new applications, the Open Handset Alliance offers the Android Software Development Kit. The Android platform is a software stack for mobile devices including an operating system, middleware and key applications. Developers can create applications for the platform using the Android SDK. Applications are written using the Java programming language and run on Dalvik, a custom virtual machine designed for embedded use, which runs on top of a Linux kernel.