APIs Made Simple: What They Are and How They Work

In this article, you will learn everything you need to know to understand what an API is, why are they everywhere even if you know nothing about tech. We will try to use simple analogies and keep this article free from jargons and simple to understand while still keeping it accurate.

APIs are fast becoming the language of the internet

What is an API?

An API, or Application Programming Interface, is a set of protocols (agreed rules), routines, and tools that developers use to build software applications. Simply put, an API allows one software application to interact with another software application, and access its functionality and data.

Have you ever wondered how you are able to use your Google or Facebook account to sign in to other apps and websites? The answer lies in APIs.

APIs have become an integral part of modern software development and are used in a wide range of applications and industries. In fact, according to ProgrammableWeb, a leading directory of APIs, there are over 26,000 publicly available APIs today (while I believe the actual number may be way more than this and growing every minute).

Some of the most popular apps and services that use APIs include:

Facebook: Facebook’s Graph API allows developers to access user data, such as profile information and friends lists, and integrate Facebook features into their own apps and websites.
Twitter: Twitter’s API allows developers to access Twitter’s data, such as tweets and user profiles, and build apps that interact with the Twitter platform.
Google Maps: Google Maps API allows developers to integrate Google Maps into their own websites and apps, and access features such as geolocation and directions. This makes embedding maps into other applications easy. (example – find the closest ATM branch using a bank app etc.)
Uber: Uber’s API allows developers to build apps that integrate with the Uber platform, such as apps that allow users to hail an Uber ride from within the app.
Spotify: Spotify’s API allows developers to access Spotify’s music catalog and build apps that integrate with the Spotify platform.

As you can see, APIs are used by some of the most popular apps and services that we use in our day-to-day lives. Without APIs, it would be much harder for developers to build software applications that interact with each other and provide the seamless experiences that we have come to expect.

Understanding APIs

To understand what an API is, let’s use an analogy.

Imagine that you’re planning a trip to a foreign country and you don’t speak the local language. You want to communicate with the locals, but you don’t know how to speak their language. So, you decide to hire a translator to help you out.

The translator acts as an intermediary between you and the locals. You tell the translator what you want to say, and the translator translates it into the local language for the locals to understand. Likewise, when the locals speak to you, the translator translates what they’re saying into a language you can understand.

In this scenario, the translator is like an API. An API acts as an intermediary between two different programs or websites. One program (let’s call it Program A) needs to use some information or functionality from another program (Program B), but Program B may use a different language or format that Program A cannot understand.

Just like how you hired a translator to communicate with the locals, Program A uses the API to communicate with Program B. The API translates the information or functionality from Program B into a language or format that Program A can understand.

Just like how you have to pay the translator for their services, Program A may have to follow certain rules and requirements set up by Program B in order to use its API. This is because Program B wants to make sure that its information and functionality are being used properly and securely.

So, in essence, an API is like a translator that allows different programs or websites to communicate with each other in a common language or format. It facilitates the exchange of information and functionality between different programs or websites that might not otherwise be able to communicate with each other.

In the world of software development, an API acts as an intermediary between two applications, allowing them to communicate with each other and exchange data. When a developer creates an API, they define a set of rules and protocols that specify how other developers can interact with their application. This includes what types of requests can be made, what data can be accessed, and how the response will be delivered.

Types of APIs:

There are three main types of APIs:

Open APIs: These are publicly available APIs that can be accessed by any developer. They are often used to create third-party applications and integrations. Examples: Facebook or google maps APIs that allow them to communicate with other programs / apps / websites. These are ‘open for all’ to use.
Internal APIs: These are APIs that are used within an organization to enable different systems and applications to communicate with each other. They are not usually available to external developers. Examples: Google Maps may internally use some other google APIs to allow the functionality or close integration between 2 products of the same organisation like Facebook and Instagram that a third party application can’t provide.
Partner APIs: These are APIs that are created specifically for a partner or group of partners, and are often used for business-to-business (B2B) integrations.

Regardless of the type of API, the goal is to provide a standardized way for developers to interact with an application, without requiring them to have access to the underlying code. This allows developers to create new applications and integrations more quickly and easily, without having to start from scratch. The above categorisation is based on who those added interactions are available to:

Everyone (Public)
Selected other businesses (Partner)

Internal teams / products only (Internal)

How APIs Work

So how do APIs actually work? Let’s break it down into a few simple steps:

A developer creates an API: When a developer creates an API, they define a set of rules and protocols that specify how other developers can interact with their application. This includes what types of requests can be made, what data can be accessed, and how the response will be delivered.
A developer makes a request: When a developer wants to access the functionality of an application through an API, they make a request. This request is typically made in the form of an HTTP request, which is a standardized way of sending requests and receiving responses over the internet.
The API processes the request: When the API receives a request, it processes it according to the rules and protocols that were defined by the developer. This may involve accessing data or performing a specific action within the application.
The API sends a response: Once the request has been processed, the API sends a response back to the developer. This response typically includes the requested data or an acknowledgement that the requested action was completed successfully.

It’s important to note that APIs can also be used to restrict access to an application’s data and functionality. For example, an API may require developers to authenticate themselves using a username and password before they can access certain data or perform certain actions. This helps to ensure that only authorized users are able to access sensitive data or perform sensitive actions within an application.

So APIs provide a standardized way for applications to communicate with each other and exchange data. They have become an integral part of modern software development and are used by some of the most popular apps and services that we use in our day-to-day lives. By understanding how APIs work, developers can create new applications and integrations more quickly and easily, without having to start from scratch.

Key components of an API

APIs are easier to understand as components

To keep things simple, we will try to explain the different components of an API and take examples from a REST API which is (arguably) the most commonly used form of APis

If we were to create an API today, we would need to provide users (client applications) of the API answers to the following questions:

Where – (on which server / IP address) is your API located so users can make the call to it?
Which Version – If there are multiple versions hosted, how can I call any single version explicitly?
Resource – If your API allows me to READ, WRITE, UPDATE and DELETE (also called CRUD operations) certain resources; what is path for each resource? Example of a resource would be: User or Product etc.
Auth – How would a user (client) get authorized to use the API? (Unless the API is free / open for all and doesn’t need to identify the calling user/application)
Content-Type – Information about the type of content being sent (so it can be parsed / read correctly). Example – JSON or XML etc.
Body – Data of the request.
Other API specific information needed.

One option that may be confusing in this list may be #2 (Which version). Why would we need multiple versions of APIs?

Assume as situation where we host an API that many apps connect with. If we add new functionality in the new version needing additional / different parameters to call the app; this may also mean that all apps that call our API also need to update their calls (hence their apps) else their app will have broken functionality (they will still make cals based on older contract that we don’t work with anymore). In such a case, we may choose to host multiple versions allowing connecting applications to decide and use the versions whenever they are ready. This is also known as ‘backwards compatibility’.

Examples of APIs in Everyday Life

APIs are used in a wide variety of applications that we use every day. Here are a few examples:

Social Media: Many social media platforms, such as Facebook and Twitter, have APIs that allow developers to create third-party applications that can access user data and post updates on behalf of users.
Weather Apps: Weather apps often use APIs provided by weather services to access real-time weather data and display it to users in a user-friendly format.
Mapping Applications: Mapping applications, such as Google Maps and Waze, use APIs to access location data and provide users with real-time navigation and traffic information.
Online Shopping: E-commerce platforms, such as Amazon and eBay, use APIs to enable sellers to list products, manage orders, and access customer data.
Payment Systems: Payment systems, such as PayPal and Stripe, use APIs to process payments securely and seamlessly across different platforms.

These are just a few examples of the many ways that APIs are used in our day-to-day lives. APIs have become an essential tool for developers to create new applications and integrations quickly and easily, without having to start from scratch. By using APIs, developers can leverage the functionality and data of existing applications and services, saving time and resources in the development process.

Benefits of Using APIs

APIs provide several benefits to both developers and businesses. Here are a few of the key benefits:

Increased Efficiency: By using APIs, developers can save time and resources by leveraging existing functionality and data from other applications and services. This allows them to focus on creating new features and functionality, rather than starting from scratch.
Improved User Experience: APIs can be used to create seamless integrations between different applications and services, which can improve the user experience. For example, an e-commerce platform could use an API to allow users to complete a purchase without having to leave the platform.
Scalability: APIs can help businesses scale their operations by allowing them to automate processes and integrate with other applications and services. This can help to streamline workflows and reduce the risk of errors.
Revenue Generation: APIs can be used to generate revenue by enabling third-party developers to create applications and services that leverage the functionality and data of an existing application or service. For example, a social media platform could charge developers to access its API and use its data in their own applications.
Data Security: APIs can be used to secure data by providing a standardized way to access and exchange data between different applications and services. This helps to reduce the risk of data breaches and ensures that sensitive data is only accessed by authorized users. Example – You can use your google login to log into multiple applications without ever having to share your google credentials with these apps. They make API call to Google to authenticate you and google responds with the result.

In summary, APIs provide several benefits to developers and businesses, including increased efficiency, improved user experience, scalability, revenue generation, and data security. By leveraging APIs, businesses can create new applications and services more quickly and easily, while also improving the user experience and increasing revenue.

Challenges of Using APIs

While APIs offer many benefits, there are also some challenges associated with using them. Here are a few of the key challenges:

Complexity: APIs can be complex to set up and use, especially for developers who are not familiar with the technology. They require a certain level of technical expertise, and developers may need to spend time learning how to use the API and integrate it into their applications.
Dependence on Third-Party Services: APIs rely on third-party services, and if those services go down or change their API, it can impact the functionality of an application. This can lead to downtime and user frustration.
Security Concerns: APIs can also pose security risks if they are not implemented properly. Developers need to ensure that they are using secure authentication methods and that they are properly handling sensitive data.
Compatibility Issues: Different APIs may have different specifications and requirements, which can make it difficult to integrate them into an application. Developers may need to spend time ensuring that the API is compatible with their application and that they are using the correct version of the API.
Maintenance: APIs require ongoing maintenance to ensure that they continue to work properly and are compatible with new technologies and updates. This can be a significant ongoing cost for businesses and developers.

While APIs offer many benefits, there are also several challenges associated with using them. Developers and businesses need to be aware of these challenges and take steps to mitigate them, such as investing in security measures and staying up to date with API updates and maintenance.

Examples of APIs in Popular Applications

APIs are used in many popular applications and services that we use on a daily basis. Here are a few examples:

Google Maps API: The Google Maps API allows developers to integrate Google Maps into their applications. This enables users to view maps and get directions without leaving the application.
Facebook Graph API: The Facebook Graph API allows developers to access data from Facebook, such as a user’s profile information or their friends list. This data can be used to create custom applications or to integrate with other services.
Twitter API: The Twitter API allows developers to access Twitter data, such as tweets and user information. This data can be used to create custom applications or to integrate with other services.
Amazon Web Services API: The Amazon Web Services API allows developers to access Amazon’s cloud-based services, such as storage and computing resources. This enables businesses to scale their operations and reduce costs.
Stripe API: The Stripe API allows developers to integrate payment processing into their applications. This enables businesses to accept payments from customers directly within their application.

These are just a few examples of the many applications that use APIs to improve functionality and provide a better user experience. APIs are a critical component of modern software development and enable developers to create powerful applications more quickly and easily than ever before.

Summary

To summarize, an API is a set of programming instructions that enables one application to interact with another. APIs have revolutionized the way software is developed and deployed, making it easier and faster to create powerful applications. They allow developers to reuse code, reduce development time, and create applications that are more flexible and scalable. APIs are used in many popular applications that we use on a daily basis, including Google Maps, Facebook, Twitter, and Amazon Web Services. While there are challenges associated with using APIs, the benefits far outweigh the risks. By leveraging APIs, developers can create better applications more quickly and easily than ever before.

As APIs continue to evolve and become more widely adopted, they will play an increasingly important role in the development of new applications and services. Whether you are a developer or a business owner, understanding APIs is essential for staying competitive in today’s fast-paced technology landscape.