What Is An API & How Do APIs Work? [Explained For Beginners]

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What exactly is an API?
Why are APIs important?
Examples of APIs
How do APIs work?
Automating your workflow using APIs
API FAQs

What is an API?

People who have built a successful business from the ground up are always looking for ways to scale it. One of the ways to do this is to encourage interaction with your business, and you can do exactly that by creating an API — but what is an API?

Each time you share an article you like, send a selfie to your friends, or video chat your parents on Zoom — an application programming interface (API) is doing the work behind the scenes.

Every day, we use APIs that simplify our lives and help us live and work much better and faster. They are a vital part of modern technology that fuels innovation and interconnection — but they’re often overlooked.

Anyone that isn’t already using APIs to improve their workflow is completely missing out. The problem is, most definitions are impossible to decipher — obscured by computer jargon and complicated concepts. This makes it difficult to recognize the value that an API can add to your business.

So let’s keep things simple. In this article, we’ll talk about what an API is using plain old English.

What exactly is an API?

Simply put, an API is an interface that helps software programs connect and communicate with one another.

The keyword here is interface — a point where two systems, subjects, organizations, and so forth meet and interact.

Another type of interface you might be familiar with is the user interface (UI). Most of the programs you use have their own UI.

These UIs let you provide your own input to tell programs exactly what you need them to do. In other words, they help you (the user) interact with whatever program you are using (user to machine).

An API works similarly. Except now, the interaction happens between software programs (machine to machine). The illustration below, from the book The Design of Web APIs by Arnaud Lauret, shows the similarity of UIs and APIs.

Why are APIs important?

Now that you know what an API is, you might be wondering why they’re such a big deal.

The short answer: APIs make things easier for everyone.

To show you what I mean, let’s take this beautiful map of California as an example.

Obviously, we didn’t code this map into the website — not only would that be a huge waste of time, but also a huge waste of resources.

Instead, we embedded the map from Google Maps using their Maps Embed API.

But what if we didn’t? What if this Google Maps API didn’t exist?

Well, then we’d probably just tell you our address…

Showing you an actual interactive map with exact GPS coordinates would be too much work. We’d have to look up the coordinates and generate geographical and topographical data — all through rigorous, manual coding.

Not only would it be incredibly time-consuming, but the map widget would also be buggy, inaccurate, and terribly ugly.

Luckily, Google has done the work for us and has been generous enough to share their API to the public. All we have to do now, to make a map appear, is use a short strip of HTML code.

By leveraging the connectivity that APIs provide, developers can work more efficiently and get more things done.

Instead of writing code that’s already been written before and wasting precious time, developers can focus their efforts on the big picture — innovation. APIs help keep them focused on the mission.

And, to tell you the truth, humanity would not have come this far without the help of APIs. It’d be like living in a world of fancy sportscars and no way to steer.

Almost every system in the world leverages an API to keep things going. Without them, services, processes, and activities around the world would grind to a halt.

The world would crumble.

So, every time you share an article you like, send a selfie to your friends, or video chat your parents — you can thank an API for making it happen.

Examples of APIs

APIs are present in most of the applications you use. Here are some very familiar ones:

Follow Button API by Twitter

Lets you follow a Twitter profile outside of Twitter using an embedded Follow button.

Like Button API by Facebook

Lets you like a Facebook page outside of Facebook using an embedded Like button.

Subscribe Button API by YouTube

Lets you subscribe to a YouTube channel outside of YouTube using an embedded Subscribe button.

Other APIs

The ones listed above have relatively simple functionalities with everyday uses. Some APIs have much more bearing on the way we live.

Here are a few ways APIs are used behind the scenes:

Banks use private APIs to manage checking accounts and process transactions
Logistics companies use APIs to track parcels and communicate with retail partners
Unified communications products aggregate various digital communication media into a single interface via APIs, which streamlines communication

How do APIs work?

By far the best analogy for the way APIs work is the waiter analogy — one that Mulesoft explains perfectly in their short, 3-minute video called “What is an API?”.

In the waiter analogy, the user is a hungry customer at a restaurant. After some time browsing the menu, he makes up his mind on a meal he likes. But before he can chow down on his meal, two things must happen:

His order must get to the kitchen, and
His cooked meal must get to him

Luckily for him, there are people equipped with the skills to perform both these tasks — waiters.

The waiter is the unsung hero of the food industry, responsible for providing seamless interactions between the customer and the kitchen.

When it comes to software-to-software interactions, APIs do the same thing. An API takes your request (your order) to the system (the kitchen) and returns to you with your desired response (your meal).

This desired response is usually data or a functionality.

If, for example, a developer wants to create a productivity app that can share the user’s achievements on Twitter, all she has to do is use Twitter’s Tweet Button API.

Similarly, if a digital marketer needs to aggregate Twitter data into Google Sheets for sentiment analysis, you guessed it — they use an API.

Automate your workflow using APIs

Even though documentations are often well-written, people outside the tech industry will lack the skills to effectively integrate APIs into their workflow without proper guidance.

You need a solid grasp of programming (and computers in general) to put the documentations to use, so it’s usually developers who use APIs.

But now, the power of APIs is at your fingertips — and you don’t even have to be a developer.

If you do SEO consulting, trade stocks, or run your own e-commerce store — you probably use Google Sheets more often than you’d like, but not as efficiently as you want.

Some of the tasks you do are so mechanical that you wonder why robots haven’t replaced you yet — importing data from Google Analytics, copying stock prices from Bloomberg, and updating prices on your e-comm website — all complete chores.

Now, you can use APIs to automate them.

No scripts. No coding.

Of course, this does mean you’re letting robots replace you for some essential tasks — but now you can focus on things that actually require your irreplaceable, human input.

Check out the video below to see how you can use Google Sheets like a true pro.

API FAQs

Frequently asked questions about APIs.

What does API stand for?

API stands for Application Programming Interface.

What is a REST API?

REST stands for Representational State Transfer. A REST API is an API based on the REST architectural style. Essentially, REST is a set of rules for developers to follow, and it decides how an API looks like. REST APIs are also called RESTful APIs. Their meanings are the same.

What are the types of API?

Mainly, there are 4 types of API:

Open APIs

Open APIs, also called Public APIs, are APIs made available for public use. They usually require prior registration to the provider’s service, use of a Key & Secret or OAuth. Some, however, are completely open. The examples in the earlier section are Open APIs.

Internal APIs

Internal APIs, also called Private APIs, are APIs only made available within an internal system. They are usually used within companies to improve products, services, and workflow.

Partner APIs

Partner APIs are APIs available only to specific parties. Like Internal APIs, this means they are not available to the public. The only thing that differentiates Partner APIs from Open APIs is who can access them.

Composite APIs

With other types of APIs, you often must make a request for each desired response. If you want to make multiple requests, you must make multiple round trips to a server. Composite APIs batch requests into a single API call, which saves time.

Are APIs secure?

Yes. Mostly. APIs are permission-based. Think of them like contracts. You do not have to sign if you disagree with what a contract says. In the same vein, you decide how much data you can share via an API.

Well-designed APIs provide secure connections to third-party applications. In many of the commercial apps you use, APIs pave the way for fast and secure transactions. They are are the reason you can use PayPal to pay for your Amazon purchase without using PayPal’s own app.