Google calendar, Google map, Google mail, Yahoo mail, WhatsApp, Signal, Facebook and Onenote are the must-have apps on my phone, especially Google calendar, Google map, WhatsApp and Signal. I can say I can not live without them now. I do save all of the important events in Google calendar and it's convenience to review my schedule. I have a poor sense of direction and therefore I need Google map if I visit a new place. WhatsApp and Signal are two of the most famous communication apps nowadays. I must have them to keep contact with my relatives, friends and colleagues. Onenote is one of the apps that I have been using recently. I use it to keep my English lessons notes and recipes that I love (its function for me just like a cookbook). I can check a recipe easily during cooking.