How do Mobile Apps Work?

Sarah Smith
14 min readJan 21, 2021

Many of us use apps every day. But we don’t often stop to think: how do mobile apps even work?

In this article I’ll be digging into how apps work to connect people with things they value, and how that works for your business. I’ll talk about app development, the cloud, the app stores, and some other technical stuff — but we are going to be keeping it light on the jargon.

It’s the first post in a series “How do I build an app?”. See the series introduction for a list of other articles in the series.

Let’s dive in.

Apps are part of the fabric of the Internet

Apps seem simple when you look at them! But we know companies like Facebook and Google; Twitter and Snapchat have hundreds, even thousands of people working on apps.

A large and wide auditorium is full of people in caps & t-shirts watching a speaker in front of multiple screens.
How do apps work? A lot of the code runs in the cloud. Around a thousand engineers on their laptops in one room at Brisbane Convention Center for the Google Cloud on Board event 5 March 2019 © Smithsoft

When I tap an icon on my phone the Twitter app opens up. But all those engineers working on code for apps: what happens to all that code?

What about even a simple app like the notes app that comes with my phone? Surely most of that simple app is just what you see on the surface?

Apps use the Cloud to provide functionality

The answer of course is that even a simple app is more than just the icon and the application itself on your phone. Much of the functionality of apps is actually in the cloud. Even the humble notes app is saving data into the cloud. For some apps, and Facebook is a great example, the mobile app is just a small windows onto a huge web-based system. No wonder they need all those engineers!

Graphic of a laptop displaying a cloud download dialog, light lines suggest a cycle in the background.
Cloud download: much of apps is actually cloud functionality — image credit:

So what is the cloud? Just in case you need a refresher let’s take a minute to go over ”the cloud” as it relates to apps.

Sidebar: Cloud Refresher

Think about a television station. It broadcasts, day and night, waiting for someone to tune in with their TV set. We don’t know where the television station is. When we tune in we just see the shows that the television station is broadcasting.

Sarah Smith

Sarah Smith is a writer & app developer .