Android is an open source operating system developed by Google and the Open Handset Alliance for use on mobile devices. It features a Dalvik virtual machine, integrated browser, multimedia codecs, Bluetooth, WiFi, GPS and other hardware integration. Apps run in a sandboxed environment with limited RAM and storage. The Android SDK allows developers to create apps that take advantage of mobile opportunities like location services, games and information on the go, while addressing challenges like intermittent networks and small screens. The document provides suggestions for sample student projects involving web scraping, multiplayer games, and location-based to-do lists.