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The Basic Parts of a Mobile App


Daniel Ra

Have you ever wondered what goes into a mobile app that you use on your smartphone? Wonder no more! There’s no magic to the apps we use. While we won’t dive into nitty-gritty details of a mobile app’s architecture, this easy-to-understand diagram should give you a good foundation to communicate your needs with us. We’ll start with this diagram here:

Diagram of a mobile app

Let’s describe these parts, starting from the left:

At 9 o’ clock, you’ll see Services. Services contain the business logic and data sources for the app. Apps talk to these services through an Application Programming Interface (API), which you can think of like the cord that plugged into the back of Neo’s head. When folks talk about “the cloud”, this is what they’re typically referring to. These services may be first-party (built by the app’s company), or third-party (using one or more services made by someone else).

For example, in a peer-to-peer money transfer app, the first-party service may store the user’s preferences and transaction details, while a third-party service may be responsible for processing payments.

At 10 o’clock, you’ll see Libraries. Libraries are usually third-party “packages” of code that the app’s developers use to enable specific functionality out of the box. Developers use libraries so that they don’t have to write that functionality from scratch. For example, Android and iOS have proprietary libraries for built-in operating system features that developers can take advantage of, like using the operating system’s GPS capability or the fingerprint reader.

At 2 o’clock, you’ll see the App’s Codebase. This is the code that one or more developers are writing to build the app’s features and functionality. The code will reference the services’ APIs and will include the libraries that the developers use. The code also implements the user interface and interactions that the designer builds.

At 4 o’clock, you’ll see the User Interface and Experience. Designers are responsible for the crucial task of creating the look, feel, and experience of the app, which strongly influence how the user feels about it. The designer’s work is directly coded into the codebase by the developers, as I mentioned just previously.

These parts work together to make an app that you enjoy using!

From product ideation to distribution, Big Nerd Ranch is world-renowned for building best-in-class mobile solutions. We’d be delighted to work with you on designing and building your UI, APIs, or all of it towards an app that positively impacts your business goals.


Daniel Ra

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