What is an API?

In our technologically driven world, not a day goes by where we're not scrolling away on our phone's apps or surfing all corners of the web. But have you ever stopped and wondered how your phone and computer are able to interact with apps and websites in the first place?

Most of us would probably say the internet or an app installation and leave it at that; however, there's a little more to it than this. Much like how your phone's touch screen is an interface for you to communicate with the phone's software and apps, so too does a computer need an interface to speak with websites and their servers.

This is where APIs come in – software specifically designed to facilitate just that. So, for those unfamiliar with APIs, this article is going to cover what they are, how they add security to your actions online, and how you can potentially integrate an API into the online aspects of your business.

As when discussing any kind of software, there's a lot of technical jargon surrounding the question, 'what is an API?' So, to keep things simple, we'll start by answering the question, 'what does API stand for?'

API stands for Application Programming Interface, and its purpose is as simple as it sounds. APIs are literally software intermediaries that provide a set of functions and procedures to enable computers to seamlessly communicate with apps, other computers, and websites, sharing information and data between them. This provides a secure way for different pieces of software to talk to each other and enhance each other’s functionality.

As you can imagine, this makes APIs an incredibly useful and important piece of software, and they're in use with just about everything. For example, most major websites you can think of will make use of APIs in some capacity. Whenever you send mobile payments or use your favourite apps, you’re using an API without even realising it.

APIs today

Over time, APIs have become much more standardised as their use has increased. Nowadays, APIs are viewed more as products rather than code, and this level of standardisation and monitoring means that APIs now benefit from even stricter security and performance requirements.

Modern APIs ensure robust security while still enabling the quick and easy sharing of data between different applications and devices. For example, when data is shared between your phone and the app you’re using (such as location data), only small packets of data are communicated so that only necessary information is shared. Each application or device is never fully exposed to the other, ensuring that data privacy is protected.

What are the benefits of APIs?

Thanks to the rise of mobile apps and online transactions, APIs are now an incredibly valuable asset for businesses. With APIs, businesses can share data, meet customer demand and innovate faster than ever before, allowing them to meet ambitious growth targets.

APIs bring many benefits to business owners and end users alike, including:

Enhanced customer experience through fast data sharing (enabling things like location services and app integrations).
Improved data transfer speeds.
Improved operational efficiency, leading to improved productivity and profits for businesses.
The ability to better integrate new applications with existing software systems.
Rapid innovation and development due to the ability to leverage existing code with APIs rather than starting from scratch.

How do APIs work?

From an aerial viewpoint, watching how an API works might look as simple as its basic definition.

Imagine that you want to log onto a website, and you get the choice to log in using Facebook or Google instead of setting up a separate account. If you choose to log in with Facebook or Google, the site's API is activated and a request is sent to the relevant server.

This server will confirm your authenticity, potentially using an accompanying API key, retrieve your requested data, interpret it into a readable format for the website in question, perform any other action necessary, and then send the data back to you. The API will then interpret this data and display it in a way that you can understand.

Naturally, with so many websites using APIs, and so many users using each website, the number of requests handled by any one API is potentially enormous.

What is an API gateway?

To overcome the issue of overburdening a site's API, many websites implement what's known as an API gateway. An API gateway sits 'behind' the API and intercepts all requests that come in. It then splits up these requests and diverts them to the relevant backend systems for a quicker response.

This helps to streamline the sending and receiving of data for efficient website, app, and computer navigation, while also providing an increased layer of security as API gateways handle authentication and security requests as well.

What is an API key?

Given the importance of APIs in nearly everything, you'd expect all APIs to be highly secure to protect them from malicious use, which is why so many APIs are equipped with more than just an API gateway.

An API key is a code or identity token that serves as a unique identifier for the user in question when they make an API request. This code is read by the API and can be used to authenticate that a user is who they say they are, authorising their access to the API database in question.

The use of an API key offers API users an extra degree of security by providing a verification system, as well as blocking anonymous users, and controlling who can use the API in the first place.

What is a REST API?

Of course, there are a variety of different API types out there, each offering varying levels of security. Fortunately, the most common format of API is also considered the most secure.

Known as RESTful APIs, these APIs are made using the REST (Representational State Transfer) architectural style, giving them an excellent degree of flexibility thanks to the wide range of programming languages compatible with REST.

But it's not just flexibility that RESTful APIs come with. They also receive the following benefits:

Client-server decoupling: With REST APIs, client and server applications are always completed independently from one another, preventing them from interacting outside of passing information.
Statelessness: REST APIs work on a stateless model, which requires requests to have a specific set of information in order for said requests to be processed, meaning servers can't store any data relating to a client.
Layered system architecture: RESTful APIs don't allow the client sending the requests and the receiving server to communicate directly. Instead, a request is sent through a variety of intermediaries, so the client and server are never sure if they're directly communicating with one another.

As you can imagine, the use of a RESTful API gives you even greater security by minimising the risk of malicious data being sent or received. Of course, REST is not the only architecture in use.

What is a SOAP API?

Another architectural style used for APIs is SOAP (Simple Object Access Protocol). While REST is a more common and simpler method for building APIs, SOAP is much more strict and secure. SOAP APIs use XML to send messages between the server (e.g. a database) and the client (e.g. a mobile app).

When considering REST vs SOAP, the simple difference is that SOAP is a structured protocol, whereas REST is much more flexible and less defined. Since SOAP APIs require a standardised structure, they can be more complex to work with, but the benefit is that these APIs are extremely secure. Plus, SOAP APIs can work with any transport protocol, whereas REST APIs rely on the underlying transport protocol (usually HTTPS). This can give REST APIs better performance than SOAP APIs, but they can suffer in terms of security and backward compatibility.

SOAP APIs were more popular in the past, but REST APIs have become the preferred API over time due to their superior flexibility.

What are the different types of APIs?

In addition to having different architectures, APIs can also have different scopes of use. This means there are multiple types of APIs depending on how and why you’re using them. Here are the main ones to be aware of:

Public APIs: These APIs can be used by anyone, but they may come with a cost or some level of authorisation.
Private APIs: These APIs are private to a particular organisation, so they only transfer data within this enterprise.
Partner APIs: If you have a business-to-business partnership, these APIs can be used by authorised external developers to facilitate data exchange.
Composite APIs: If you have more complex requirements, you may need to combine two or more different types of APIs to create a composite API.

What is API testing?

Given the level of security APIs provide in the sharing of data, it should come as no surprise that they're heavily utilised in the world of business. A fluid and uninterrupted customer experience is a must for any business with an online presence to help drive revenue. This makes API testing a necessity.

On a surface level, API testing is all about ensuring that the API you use meets the level of functionality, reliability, performance, and security that you require. Using API testing software, the API can be analysed to see if it meets your criteria, either directly on the API or as part of API integration testing.

By utilising API testing, you can test and measure response times to bring your site up to speed to handle customer requests and ensure a good customer experience.

What is API integration?

Lastly, we'll touch briefly on API integration. Many businesses, especially those with multiple working parts on a software level, need a way to automate the requests between them.

API integration allows them to do this by interconnecting all the APIs in use to their various software so that they can seamlessly connect and communicate. Automating the system's APIs allows the exchange of data to occur faster, making everything more efficient by minimising human input.

While not necessarily beneficial for small businesses, the added functionality this presents to large businesses should be obvious.

How to use API software

Sadly, understanding, creating, and implementing your own API is a complex topic, one which is far outside the scope of this article. However, if you're wondering how best to use API software and implement its use in your own business, there are plenty of tutorials and courses online that can get you started.

At a basic level, using API software involves establishing a client-server relationship. In this relationship, both sides must adhere to certain rules and follow the right protocols. For example, the client must submit all parameters and headers correctly in the API request, as this will allow a successful response from the server.

To implement your chosen API, you’ll need to follow a clear step-by-step process:

Define the goal of your API (for example, do you want to increase profits, improve customer experience, or improve development speeds?)
Designate a data source for your API.
Create an API diagram (detailing the parameters, protocols, data and more).
Choose an API architecture (e.g. REST vs SOAP).
Select an authentication method, such as API keys.
Develop your API documentation.
Deploy, test and monitor your API.

As you can see, the steps above are very top-level. API integration varies depending on your goals, but this should give you a rough idea of what to expect.

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