Mobile phones have made a bigger difference to the lives of people, more quickly, than any previous communications technology. They have spread the fastest and proved the easiest and cheapest to adopt. It is estimated that more than 5 billion people currently have mobile phones and more than 6 billion will have them in 2013. Mobile phones have already started functioning as more than just communications devices. Mobiles serve various functionalities like watch, alarm, calculator, calendar, reminder, games etc. Smartphones are fastest and becoming a feasible alternative to PDAs and laptops, offering phone features such as voice and SMS coupled with mobile internet applications, multimedia functionality, high speed data processing capabilities, and inbuilt GPS capabilities. Indeed, there is a wealth of operating systems for smart phones and each provider has its own download platform and applications. One reason for increasing popularity of mobile devices is the gain in productivity and efficiency, particularly for professional on the go. From health care workers to sales people in the field to workers who simply move from their office to conference room, mobile devices enable seamless access to full range of corporate. In early 2011, five major operating systems emerged on the international stage.When choosing a smart phone or mobile phone; it will be equipped with a certain operating system. An operating system is a platform that structures the functionalities of a mobile device and makes them accessible for its user. Some OS are linked to specific phone brands, other OS can be installed on several phone brands. These devices connect to a wide spectrum of networks including the internet and intranets and transmit secure data across the network. The popularity of these devices expected to make them secure. There are number of platform and lack of repository that describes these platforms, developer and user may not know which is best for them. This paper explores functionality and includes inclusive analysis of mobile operating system on the bases of functionalities, performances, security. This paper provides what functionalities OS manufacturer can implemented on various hardware platform and what security they can provide with various operating systems versions for attracting various customers of each kind.