When you talk about why people consider certain mobile apps to be successful, famous or popular and why people think of certain mobile apps to be a total failure then you need to understand that the success or a failure of a mobile app is based on how useful the mobile app actually is for its users and how much value does it provide. When you make an app like shareit you are providing people with a mobile app that is allowing you to share important data and information very easily, helping you save time. What other reasons might be there?