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What are apps and how do they work?

Joe MillerProduct manager
less than a minute01 December 2023

You're probably using ‘apps' several times a day – but what are they? And how does an app work?

TL;DR How does an app work?

Desktop, Web and Mobile - Different app types

Content flowing to different platforms

Desktop or laptop computers

For desktop or laptop computers, applications have become powerful tools that harness the full capabilities of their operating systems, such as Windows, macOS, and Linux. These desktop applications have intricate functionalities, taking advantage of the larger screens, robust processing power, and extended memory capacities of desktop computers. From sophisticated graphic design software like Adobe Photoshop to office applications like Microsoft Word, desktop apps cater to various professional and personal needs.

Web apps

The advent of web applications has redefined our online experiences. Accessible through standard web browsers, these applications eliminate the need for storage intensive local installations, providing users instant access to many functionalities through the cloud. Web apps range from collaborative productivity suites like Google Workspace to interactive social media platforms like Twitter and Instagram. Their browser-based nature allows users to seamlessly switch between devices, accessing the same features without compromising user experience.

Mobile apps

Mobile devices, particularly smartphones and tablets, have become integral to our daily lives. Modern applications have seamlessly adapted to the mobile landscape, offering user-friendly interfaces optimised for smaller screens and touch interactions. Native mobile apps, designed specifically for iOS or Android platforms, take advantage of the unique capabilities of a mobile device, such as GPS functionality, camera integration, and push notifications. Hybrid apps bridge the gap between native and web experiences, ensuring cross-platform compatibility while providing access to device-specific features, agnostic to a device's operating system.

A Unified User Experience

The adaptability of modern applications is not just about porting functionalities across different platforms; it's about creating a unified user experience. Whether you're drafting a document on your desktop, checking your email through a web browser, or engaging with a mobile app, the transition should be seamless between native and web apps. The consistent design language, intuitive navigation, and synchronised data ensure that users feel at home, regardless of their device.

This versatility doesn't just benefit end-users; it also streamlines development processes for app creators. With frameworks that support cross-platform development, developers can write code that works harmoniously across desktop, web, and mobile environments, reducing redundancy and accelerating the development lifecycle.

Person drawing on a whiteboard to plan how to make an app work.
User flows are a useful way to see if your app will make sense to the people engaging with it.

How are apps built?

Building apps involves a multi-faceted process that combines creativity, coding, and meticulous planning. The approach to app development can vary based on factors such as the type of app, target platforms, and desired functionalities. Here's a comprehensive overview of the general steps involved in building apps:

Defining the Purpose and Scope

Before starting any development, it's essential to define the purpose of the app and its scope clearly. Identifying the target audience, key features, information architecture (IA) and overall goals is crucial to provide a roadmap for the development process.

Choosing the Development Platform

Once you've defined the purpose and scope, it's time to decide whether the app will be developed for a specific platform (iOS, Android) or as a cross-platform solution. The choice between native, hybrid, or web-based development depends on the target audience, budget, and desired features.

Designing the User Interface (UI) and User Experience (UX)

The design phase is where the magic happens! Creating wireframes and mockups that outline the app's visual structure and user flow is critical in ensuring a positive user experience. Attention to user interface elements, navigation, and overall aesthetics will help make your app stand out.

Back-end Development

For apps requiring server-side functionality, developers work on the back-end to build databases, set up servers, and create APIs (Application Programming Interfaces) to communicate between the app and server.

Front-end Development

Front-end development focuses on creating the app's user interface based on the design specifications. This phase involves coding the visual elements of user interactions and integrating them with back end services. It's an exciting time to see your app come to life!

Choosing a Programming Language and Framework

The choice of programming language and framework depends on the development platform and type of app. Don't worry; many options exist, like Swift or Objective-C for iOS apps or Java or Kotlin for Android apps. Cross-platform frameworks like React Native, Flutter, or Xamarin allow for code reuse across multiple platforms.

Implementing Functionality

Developers code the app's features and functionalities based on the design and user requirements. This involves integrating various components, implementing logic, and ensuring smooth interactions. It's essential to make sure everything is working together seamlessly.


Testing is crucial to identify and fix bugs, ensure proper functionality, and optimize performance. Different types of testing, like unit testing or device testing across other platforms, will help ensure your app is ready for launch.

Optimising for Performance

Developers optimise the app for performance by addressing load times, responsiveness, and resource utilisation. This ensures a smooth user experience and efficient use of device resources. Nobody likes a slow app! Using an optimisation tool like insytful can give developers an clear understanding of where their app could be improved.

Implementing Security

Security measures are vital to safeguard user data and protect against potential vulnerabilities. This includes encryption, secure authentication, and adherence to industry best practices. Safety first!

Deployment - App stores and beyond

Developers prepare a completed app for deployment by creating build packages for the chosen platforms. For native apps, the app is submitted to the respective app stores (e.g., Apple App Store, Google Play Store). Web apps are deployed to web servers and distributed using specific channels for hybrid apps.

Post-Launch Support and Updates

After the app is launched, monitoring its performance, gathering user feedback, and promptly addressing any issues is essential. Regularly releasing updates to introduce new features, fix bugs, and enhance overall user experience will keep your users happy.

By following these steps, app developers can create robust, user-friendly applications that meet the needs of their target audience. Each step is unique to the development approach and requirements of the project, but with careful planning and execution, your app can be a success!

What is a Progressive Web App (PWA)

A Progressive Web App (PWA) is a web application that takes advantage of modern web technologies to provide a user experience similar to traditional native mobile applications. PWAs are designed to work across different devices and platforms, combining the best features of both web and mobile applications while working without and internet connection. Several vital attributes characterise a PWA:

Progressive Enhancement

PWAs are built with a "progressive enhancement" approach, meaning they work for every user regardless of the browser or device used. They provide all users with basic functionality and content and then enhance the experience for those with more advanced browsers or devices.

Responsive Design

PWAs are designed to be responsive, adapting to various screen sizes and resolutions. This ensures a consistent and optimal user experience across desktops, tablets, and mobile devices.

App-Like Experience

PWAs offer an app-like experience within a web browser. Users can interact with PWAs similarly to native mobile apps, including features like push notifications, offline access, and smooth animations.

Service Workers for Offline Functionality

One of the key features of PWAs is the use of service workers. Service workers are scripts that run in the background and enable offline functionality. They allow PWAs to cache necessary resources, allowing users to access the app even offline or in areas with poor internet connection.

Web App Manifest

PWAs use a web app manifest, a JSON file that provides metadata about the app. This includes information such as the app's name, icons, and the URL that should be opened when the app is launched. The manifest helps in installing the app on the user's home screen.

Secure Connection (HTTPS)

PWAs require a secure connection using HTTPS to ensure data integrity and security. This is a crucial aspect of PWAs, especially considering their capability to work offline and handle sensitive user data.

Discoverability and Shareability

PWAs are easily discoverable and shareable. Users can access PWAs directly through a web browser without app store installations. Additionally, PWAs can be shared via URLs, making them easy to distribute.

Cross-Browser Compatibility

PWAs are designed to work across different web browsers, promoting cross-browser compatibility. This ensures users have a consistent experience using Chrome, Firefox, Safari, or other popular browsers.

Faster Load Times

With caching mechanisms and service workers, PWAs can offer faster load times, improving the overall performance and responsiveness of the application.

PWAs have gained popularity as a versatile and efficient way to deliver engaging user experiences while leveraging the ubiquity and accessibility of the web. They provide a compelling alternative to traditional native app development, especially for businesses and developers looking for a cost-effective, cross-platform solution.

What types of data can apps access?

Apps can access various data types, and the extent of access depends on factors such as the app's permissions, user settings, and the platform's security measures. Here are common types of data that apps may have access to:

Device Information

Apps often retrieve basic device information, such as the device model, operating system version, screen size, and unique identifiers (like the device's IMEI or MAC address). This information helps in tailoring the app experience to the specific device.

Location Data

Many apps, especially those related to navigation, weather, or local services, request access to the device's location data. This information can be used to provide location-based services and personalised content.

Contact Information

Apps that involve social networking, messaging, or communication functionalities may request access to the user's contact list. This enables features like finding friends or importing contacts for easier communication.

Camera and Photo

Apps with photo or video functionalities may request access to the device's camera and photo gallery. This is common in social media, photography, and video editing apps.

Microphone Access

Apps that involve audio recording, voice commands, or voice messaging may request access to the device's microphone.

Calendar and Events

Calendar apps and scheduling tools may request access to the device's calendar and event data to facilitate the creation and synchronisation of events.

Storage Access

Apps may need access to the device's local or external storage to save and retrieve files. This is common in document editing, file management, and media player apps.

Biometric Data

With the prevalence of biometric authentication methods (fingerprint, facial recognition), apps may request access to biometric data for user authentication.

Health and Fitness Data

Health and fitness apps may access data related to physical activity, heart rate, sleep patterns, and other health metrics. This data is often used to provide personalised insights and recommendations.

Sensor Data

Some apps utilise various sensors on the device, such as accelerometers, gyroscopes, or barometers, to gather data for specific functionalities. For example, gaming apps may use motion sensors for interactive gameplay.

Network Connection Information

Apps may access information about the device's network connection, including the type of connection (Wi-Fi, cellular), signal strength, and data usage. This helps optimise the app's performance based on the available network conditions.

Browser History and Cookies (Web Apps)

Progressive Web Apps (PWAs) or web-based applications may have access to browser history and cookies, allowing for a more personalised experience.

It's important to note that access to specific data types is subject to user consent and the app's permissions. Mobile operating systems (such as iOS and Android) have implemented strict permission models to ensure user privacy and security. Users typically can review and manage app permissions in their device settings, providing control over the data access granted to each app. Developers are encouraged to follow the best data security and privacy practices to build user trust.

Final thoughts

The adaptability of modern applications marks a paradigm shift in how we approach digital experiences. It's not just about making apps available on different devices but crafting a holistic and consistent user journey. As technology advances, the seamless integration of applications across platforms will play a pivotal role in shaping the future of user interactions in the digital landscape.

Joe MillerProduct manager

Joe is a Product Manager at Zengenti working within the Professional Services team.

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