What Is an API?

What Is an API and How It Connects Apps in the Digital World

Final: What Is an API_

An API, short for application programming software, is a set of rules that lets different software components talk to each other. It’s like a messenger that helps apps and services share information and work together. It is used by developers to create new software, automate tasks, and even create new apps using existing features.

In this article, we’ll explore the following:

  • What is an API?
  • How do APIs work?
  • What are the benefits of using APIs?
  • What are the different types and specifications of APIs?
  • What are the common examples of APIs?


What Is an API?

APIs play an important role in our lives. Whenever you use your phone to make online payments or book a rideshare, you’re interacting with an API. They’re like connectors that help apps and services work together smoothly without starting from scratch. Basically, they’re a way for different computer programs to communicate with each other.

With APIs, it’s easy to connect to the internet and share data with servers. The server takes care of all the heavy processing, and the app shows the requested info in a way that makes sense to you. It’s all seamless and saves everyone a lot of time and headaches.


How Do APIs Work?

APIs serve as bridges that let different products or services interact without needing to know how they actually work. They make app development faster, cheaper, and way more creative. Basically, they lay down the ground rules for software to “chat” with each other.

API process has three parts:

  • User: The person who makes a request
  • Client: The platform that sends a request to the server, typically an app
  • Server: The program that responds with the requested information

Here’s how an API works in simple terms:

  • An app asks for information by making an API call or request
  • This request goes from the app to the web server through the API’s web address
  • The API contacts the outside program or web server
  • The server sends the information back to the API
  • The API gives the data to the app that asked for it

Final: What Is an API_


What Are the Benefits of Using APIs?

APIs have become a vital part of software development. Let’s take a closer look at some of the key benefits of using them.

1. Improves Collaboration

The average enterprise uses 1,295 cloud services, many of which are disconnected. APIs help integrate various cloud applications, promoting seamless communication and workplace collaboration. This means making them part of your workplace can boost productivity and improve performance.

2. Fosters Innovation

Companies need digital transformation to stand out from competitors and meet increasing customer demands. APIs help them digitize and innovate, letting them explore new partnerships, services, and markets.

Tip: Integrating APIs into your business strategy can unlock new digital opportunities. It can streamline user onboarding, data sharing, and software deployment, improving efficiency and faster time-to-market.

3. Creates New Monetization Opportunities

APIs have become so valuable. In fact, 90% of executives say this technology has become critical to their businesses. APIs and API-driven strategies also generate 35% of the organization’s revenue. In other words, contributing to the API economy can help build your audience around your brand and establish relationships with potential business partners.

Important: APIs can get hacked, which might expose sensitive customer and company data. Businesses should implement security measures like Transport Layer Security (TLS) to keep APIs secured.


What Are the Different Types of APIs?

Final: What Is an API_APIs are classified according to their availability or release policies. They can be private, public, partner, or composite.

1. Private APIs

Private or Internal APIs are not for public consumption. Some can be publicly accessible, but their interface can be accessed only by in-house developers or contractors. They can only be used for data within the business to improve internal processes, organizational solutions, and services.

2. Public APIs

Public APIs, also known as external APIs or developer-facing APIs, let developers access a company’s software or services, allowing them to build or integrate applications. These APIs can be a valuable tool for businesses, increasing brand awareness and providing additional revenue streams.

These type of APIs come in the following types:

  • Open Public APIs

Open public APIs are freely available to the public without any restrictions. They should be easy to test and use, with readily available documentation and support, even outside business hours.

  • Commercial APIs

Commercial APIs require payment, usually through subscription fees or a pay-as-you-go model. They often offer free trials to allow potential users to evaluate the API before committing to a subscription.

3. Partner APIs

Partner APIs are accessible only to authorized business partners or external developers who have signed an agreement with the publisher. These APIs are often used for integrating software between two parties or for reserving or purchasing vouchers or tickets.

4. Composite APIs

Composite APIs combine multiple APIs to address complex system requirements and other tasks. They bundle multiple API calls together to improve or speed up performance.


What Are the Common Examples of APIs?

You might be surprised that you’ve probably used APIs regularly without even realizing it. For instance, when you log in to a site using your Google account or check the weather on your phone, APIs actually make it all happen.

Many apps rely on APIs. To better understand them, let’s examine some common real-life examples you might encounter:

1. Third-Party Payment Processing

The “Pay with PayPal” option you see on almost every e-commerce website is made possible through an API. This feature streamlines online payments for products and services and enhances security by preventing sensitive data exposure and restricting access to unauthorized individuals.

2. Universal Logins

APIs make it easy to log in to websites using your Facebook, Twitter, or Google account. This saves you time and effort by skipping the process of creating a new profile for each site.

3. Twitter

Developers can access public Tweets and replies or even post Tweets through Twitter’s API. Each Tweet has core attributes, like an author, unique ID, message, timestamp, and geolocation data.

Final: What Is an API_

4. Travel Booking Websites

APIs power travel booking sites by providing access to the latest flight and hotel availability info. This makes it easier and faster for users to look for the cheapest options or know when and where to fly based on their budget. For example, the metasearch platform Skyscanner helps travelers find the best deals from their database.

Note: Travel is one of the most prominent categories in API, with Skyscanner Flight Search consistently ranking as the number one most popular API in 2020 and 2021.

5. Google Maps

Many websites and apps use Google Maps APIs to display maps, directions, and points of interest. These APIs allow communication with the map service for tasks like plotting travel routes or tracking moving items.


What Are the API Specifications?

Final: What Is an API_

An API specification offers a clear guide on how an API works, connects with other APIs, and what outcomes to expect when using it.

There are four main types of API specifications:

1. Service Object Access Protocol (SOAP)

Service Object Access Protocol (SOAP) is a simple method for sharing organized data between systems in a flexible, distributed setting. It mainly outlines the rules for sending and receiving messages by web applications. APIs using SOAP allow data exchange between systems through HTTP or SMTP for email transfers.

This method is often used for secure data transmission in enterprise web software. SOAP APIs are popular choices for payment processing, identity management, CRM systems, and financial or telecommunication services.

2. Representational State Transfer (REST)

REST, which stands for Representational State Transfer, is a software architectural style designed for applications that work over HTTP. Its key feature is statelessness, meaning servers don’t save client data between requests. This makes RESTful APIs widely used, as they allow clients to send requests, and servers process them and return the output data.

RESTful APIs are simpler and more flexible than SOAP. They use HTTP requests like GET, PUT, DELETE, and others to access server data. REST supports various messaging formats, not just XML like SOAP.

3. Remote Procedure Call (RPC)

Remote Procedure Call (RPC) is a method that helps applications interact with each other using a client-server setup. The process involves a program (client) that asks for data or functionality from another program (server), which is on a different computer within a network. The server then sends the result back to the client.

  • gRPC

gRPC is a modern, open-source API framework that falls under the RPC category. It lets client applications directly call methods from server applications on different computers, making developing distributed services and applications easier. It’s popular for communication between microservices because it supports multiple languages and offers high performance.

Developers who use this define the data structure they want to serialize, then use a protocol buffer compiler to generate data access classes in their chosen programming language. The data gets compressed and serialized in the binary format during runtime. Simply put, it makes handling data way more efficient.

  • GraphQL

GraphQL is a newer way to build software, designed for faster development, better data handling, and improved mobile use. It’s a popular alternative to REST and is used by big companies like Yelp and Shopify.

This API lets clients ask for the specific data they need, making it simple to collect information from different sources in one API call. It also has a type system to describe data, making it unique from other methods.



APIs are the unsung heroes of the digital world, working behind the scenes to connect different applications and services. They allow developers to make requests for specific information and offer a more efficient way to access and share data. They are versatile, reusable, and can be constantly adapted to create new apps and services.

Throughout this article, we’ve explored what an API is and how it powers the global digital economy, helping businesses communicate seamlessly in the same language. They can significantly accelerate your business’s growth and innovation.


Next Steps: What Now?


Further Reading (Useful Resources)

Frequently Asked Questions

What is an API Gateway?

An API gateway is like a helpful middleman between users and backend services. It takes care of API calls, combines needed services, and gives back the right results. It handles important tasks, like user authentication, controlling usage, and collecting data on system performance. It also keeps APIs safe and provides useful insights.

What is an API Documentation?

API documentation is a crucial resource that includes references, tutorials, and examples to help developers learn about an API’s capabilities and usage. It’s typically hosted on a website or dedicated portal, so it should be easily accessible and discoverable for the target audience.

Whether the API is for internal or external use, it’s important to make the documentation available for developers. It helps explore possibilities and find answers to their questions, ensuring it meets their needs.

What is API Testing?

API testing is basically about sending requests to one or more API endpoints and checking the responses to see how well the API is working in terms of communication, performance, security, and overall function. The goal is to ensure the API does what it’s supposed to and meets the standards you expect.

How can you secure your API?

API security should be your top priority. To protect your business, you need to follow API best practices. These include using trusted authentication solutions, only giving access to what’s needed, encrypting traffic, not sharing sensitive info, being careful about what data is exposed, checking input, and using a web application firewall.

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