I have been using this app since 2014.Most of the people prefer this app rather than other.Till now I dint find network issues.Concept: The concept behind is to chat, the contacts we have in our phone and the people, friends, relatives who use this app will be shown in whatsapp contacts.I used to chat with my friends, family members.It has contents like Account, chats, notifications, data usage, contacts and if you want help. use help option.It is very easy and safe to use. Design and layout: Its icon looks pretty, green coloured.Easily upload profile picture, status and videos on status.I use the smileys to express my views its really amazing and funny.Functions: its function involves sending and receiving messeges.I easily send and receive messeges.I used to send pictures and videos to my friends and relatives.Usefulness: I found this app to be very useful for me and whenever I dont have recharge in my phone and I have data recharge I send messeges whenever it is needed.whenever its new version comes, I download its new version.