A must-have app on your phone must be the app you open and close many times every day. When you buy some groceries, you need to open an app to pay for your purchase. When you have a meeting notice, you should open an app to check the time and place. When you are free, you open an app to enjoy videos online which entertains you a lot. When you contact your friends, you send them messages through another app. There are actually many apps offering the services that I mentioned above. As for me, WeChat is the must-have app on my phone. Every day, from the moment I open my eyes in the morning until the time I fall asleep / go to bed, I spend most of my time on it. I check it for over a hundred times a day and make sure I don't miss any message from others. In fact, I would feel nervous and stressed if I don't receive messages for a while. Without this app, I’d lost my passion for other things.