What Is an API and How Does It Work?

18 May 2022

Veronika Nedashkovskaya

Content Manager

APIs have become an essential part of digital products we use every day without even noticing. Meanwhile, there are over 2.3 million API-related repositories on GitHub. What is an API? And why does everybody know the acronym, but only a few can explain it?

In fact, APIs are everywhere. They work when you check the weather forecast or pay for pizza delivery. The Rocketech experts summed up everything you need to know about APIs and why they are important in web and mobile development.

API Explained

API stands for Application Programming Interface. It’s a combination of tools and functions in an interface for creating new applications, through which one program will interact with another. It allows developers to extend the functionality of their product and connect it to other software products.

When users visit an Internet page, they interact with the remote server API. It’s a server component that receives requests and sends responses. Due to APIs, users can perform various actions (built-in payments, for example) without leaving the site.

Application Programming Interface is a specific protocol that enables computer programs to interact with each other and allows them to use the functions of one application within another.

ProgrammableWeb’s API Directory currently tracks over 24,000 different APIs. There are hundreds of APIs for financial systems, social media messaging, payments, e-commerce, cryptocurrencies, and other industries and niches. The fastest-growing segment of the API is data sharing and analysis across applications.

How Does It Work?

When you use a mobile app, it also connects to a server over the Internet and sends data. The server retrieves the data, interprets it, performs the necessary actions, and sends it back to your phone. The application analyses the interpreted data and presents you with the information you requested in a readable way.

Simply put, using API features is like hiring a freelance employee to work remotely. One application instructs the other to do the job and represents the outcome as its product.

The programming interface (as in Application Programming Interface) is a “layer” between application A and application B. It launches processes that allow the two programs to exchange information and perform functions related to both sides while concealing the software’s “inner structure”. 

This approach allows you to establish the interaction between several programs without thinking about how they are designed, what software logic they are driven by and how the transmitted data is processed.

how API works

Interfaces make it easy for users and developers. Users don’t think about what is behind the usual functions in their gadgets, while developers don’t have to scrutiny other programmers’ code to connect someone else’s product to their own.

It’s called encapsulation— concealing some features to simplify the overall work and minimize the areas of software where one of the developers could make a mistake.

An API is a Set of Functions

When you rent a flat, you make a contract where you write down all significant aspects of landlord-tenant relations. Similarly, programs also make sort of agreements. They indicate how one can access another. 

The list of these functions depends on the developers. In general, there are three API methods for interacting with each other and other programs.

  1. A process that a program can execute using this API.
  2. The data needs to be passed to the API to perform the function.
  3. The data that the program will receive on the output after working with the API.

And an API is a set of such functions. It can be only one, and there can be plenty of them. Then, how they are organized and compiled depends on the developer. There are standard options, but they are not a must.

For example, you can organize them by functionality and group APIs for authentication, system access, and registration. You can separate payment APIs and even make different functions for each bank. Or you can create one API for all functions. It’s often the case for out-of-the-box solutions with a standard set of functions. Everything else usually goes at an extra cost.

What Do You Need an API?

There are plenty of reasons for API development you need to keep in mind if you consider creating your digital product

  • Encapsulation significantly improves security. 

It’s especially relevant for large-scale software products. Programs constantly perform hundreds of internal tasks without “bothering” the user or “harming” each other. It also minimizes the human error rate.

  • APIs simplify and speed up the creation and launch of new products.

Developers don’t have to reinvent the wheel each time. You can make a TensorFlow neural network API, for example, and implement it into your product rather than creating your own machine learning system.

Before Windows and other graphical operating systems, programmers had to write thousands of lines of code to create windows on a computer screen. When Microsoft provided developers with Windows API, it took only a few minutes to create them.

  • APIs make it easy to set up relationships between different services and programs.

Owners of different applications don’t have to communicate with each other. Developers can implement support for third-party services without contacting their creators at all.

  • APIs save time and cut costs.

With thousands of APIs available for any functionality, you may pay for fewer development hours in the end.

  • APIs are the necessary instruments in microservices infrastructure.

If your product includes creating a developed microservices infrastructure, you need multiple APIs to ensure smooth communication between the software components.

Types of APIs

There are global products with separate programming languages, intended to solve local problems. There are also products for:

  • Managing various graphical components of program modules (wxWidgets, Qt, GTK, etc.);
  • Operating systems (Amiga ROM Kernel, POSIX, Linux Kernel APIruen, Cocoa, OS/2 API, Windows API);
  • Sound (DirectMusic/DirectSound, OpenAL).

And there is an API release policy that determines the degree to which the technology is available to different users.

  1. Private APIs are proprietary products intended for internal use only.
  2. Partner APIs grant access to technology only to individual business partners.
  3. Open (public) APIs are publicly available to anyone.

In general, the interface type depends on the tasks it should solve. APIs differ according to functions, purposes, and technical capabilities. There are standard products and alternative solutions. The latter can solve the same problems with other methods.

API Examples

To understand API meaning and underlying principles, you should think of data delivered on a specific request by a client or other application. Let’s say we need to get information from an existing website and transfer it to the program. There will be a request in the browser expecting an HTML response. Using an API makes it possible to perform an action related to program A in program B without the unnecessary transition to a third-party source. Here are some examples.


Google Calendar and Apple iCal are the most famous API examples. Android and iOS APIs allow developers to connect their calendars directly to third-party applications. Businesses can embed calendar APIs on their sites, for example, for customer appointments and scheduling, while end users have their data synchronized and accessed easily across apps and devices. APIs allow you to create new events and reminders, delete existing ones and edit them.

Buttons

Users don’t like long authentication processes requiring emails or phone numbers. Today, most services and applications allow them to log in through Facebook, Google, or Twitter. It’s also done through respective APIs. In this case, companies providing such APIs create a set of protected functions that you can connect to your project with minimum expenses. It’s a convenient and safe authorization way that saves time and improves the user experience.

Maps Integration

Whether it’s food delivery, taxi service, or a fitness app for runners, most users experience integrated navigation every day. Google, Apple, and a couple of other large corporations give access to their map data also through API. It can be complex use cases with extended functionality and real-time geolocation or a simple location map for an around-the-corner business.

Final Thoughts

Although people outside the IT sector probably wouldn’t know what the API acronym stands for, it becomes more widespread as our everyday lives get more digitized. Initially, API technologies were created to simplify the development process. It’s a convenient instrument — a set of classes, functions, procedures, and standards — that allows applications to communicate effectively with each other.

At Rocketech, we value our Partners’ time and always adjust our development processes to the project budgets. And APIs are an integral part of our expertise and development process. Whether your product requires a payment system integration or advanced microservices infrastructure, our specialists will advise on the best and most cost-effective way to implement it. Do you have a product idea? Contact us today!

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