An application specifically designed to run on smartphones and tablets. Like pocket-sized tools that you can use anywhere.
Instagram, Uber, and WhatsApp are mobile apps that let you share photos, get rides, and send messages from your phone.
A mobile app is an end-user application (iOS/Android), not a single cloud service. Cloud providers offer supporting services to build, host backends, authenticate users, store data, send notifications, and monitor performance, but the app itself runs on the device.