At present there are many mobile phones operating systems available in the market but mobile phones with android OS have now become domestic product which was once extravagant product. The reason towards this change is attributed to its varied functionality, ease of use and utility. There are number of tasks performed on it like making call, sending or receiving SMS, music, billing, online shopping, online booking, playing games, web browsing, using different apps like whatsapp, facebook or Applock etc. Hence a large amount of user sensitive data is stored within the devices [1]. Increased usage of smartphone has led towards higher concerns about security of userprivate data. Due to android as an open source mobile platform, user can easily install third party applications from markets and even from unreliable sources [2]. Thus, Android devices are a soft target for privacy intrusion. Whenever the user wants to install any application, firstly it’s the description and the application screenshots which provides an insight into its utility. The user reviews the description as well as a list of permission requests before its installation. As the types and rate of malicious attacks increases, the difficulty of examining in advance whether an app is malicious or not through its descriptions has increased manifolds. In this paper we have reviewed and examined android software stack and compared smartphone based operating system like android, iOS, blackberry, Symbian, windows phone, webOS, Ubuntu and firefox.