How Do APIs Work? The Complete Guide for API Development in 2021

API definitions vary depending on who you ask. But almost anytime you ask, “How do APIs work?” the answer will involve some slew of semantics having to do with the concept of connection. 

And for the question, “What is an API?” the answer is largely the same. APIs facilitate a connection that is integral to software development.

What exactly is that connection? It’s hard to say in so few words. But if you’re willing to take the time to find out, keep reading. 

What Is an API?

What are APIs? An application programming interface (API) defines how two or more technologies communicate with one another. 

This occurs on the back-end side of development, meaning it’s one of the processes end users are typically unaware of. 

Still, the use of APIs as part of the software development process is a feat of the modern technology-driven world. 

Here are a few examples of how APIs operate:

  • Looking for a flight for your next getaway? Surely, a quick Google search, putting in the keywords from destination A to B will prompt a convenient snippet of search engine results featuring outputs from different airlines pulled from all over the internet.
  • Perhaps you’re finally ready to check out your online shopping cart on eBay. Too tired to put in your whole credit card number? No worries. You can purchase your items through the PayPal app embedded into the checkout process.
  • Feeling peckish and need a bite to eat? Peruse Yelp for the best local food spots, click on the address, and it’ll take you straight to Google Maps.
  • Need to play your favorite song from Spotify? Ask Siri and she’ll make it happen without a second thought.

All these things happen on account of API integration connecting machines of different capacities and abilities together. While humans connect to these machines in a tangible way, APIs connect machines to each other and provide services like the examples above. 

Metaphorically, you can think of APIs as a user interface (UI) for machines to interact with. That is, it is the front-facing component for technologies on the back-end. 

How Does an API Work?

On the surface, an API might look like a block of code. But in reality, APIs are much more.

On the back-end, APIs sit in the middle of the application and the server. The user asks the application to perform a task and the application uses the API to meet the demand. The API, in turn, must send a call to the server in order to make a formal request.

APIs might look like a block of code. But in reality, APIs are much more.

Essentially, APIs must know how to talk to the databases and servers they pull data from every time a request is made. Specific actions trigger these reactions from the API like Googling a flight, for example. 

A common abstraction to explain, “How do APIs work?” is a waiter. A waiter is the non-technical version of an API. Waiters take orders from customers and bring them to the kitchen, delivering the final product to the customer. 

What Are APIs Used For?  

There are two principal use cases for APIs: internally and externally. Internal APIs are alternatively called private APIs. While external APIs can be used interchangeably with open APIs. 

Internally, software development teams may use APIs to ease development from the inside out. For instance, internal teams can utilize APIs to build features for their customers and/or share resources. 

Companies of any kind have moving parts that cannot be publicly shared. Internal APIs are pretty standard to software development companies. But no one outside the company can say exactly what they are. 

Still, private APIs significantly reduce development time by connecting different back-end systems and improving application functionality. 

External APIs are designed to be widely accessible. Developers from a certain company may have published their APIs in the public sphere. Or developers can release non-company-specific APIs publicly.

Open APIs are put to use largely in the same way internal APIs are. Though just about anybody who knows how to use them can access external APIs, they have the same aim as internal APIs in that they speed up development. 

In simpler terms, APIs are used for automating programming processes. Instead of coding line by line the function or program that will connect two technologies, you can simply plug an API towards the same purpose. 

What Are the Advantages of APIs?

There are numerous advantages to working with APIs, so many that you probably don’t even realize that you’re already working with an API right now and reaping the benefits.

Here’s a quick breakdown of the main advantages of APIs. 

Abstraction

One of the biggest advantages of APIs lies in the answer to the question, “How do APIs work?” APIs foster connectivity between multiple technological systems. 

This modernized way of eliciting functionality abstracts the relationship between code and the service it provides in an intuitive way. To that effect, the abstraction results in practical API integrations that are easier to implement than otherwise. 

Automation

Through automation, developers are guaranteed speed. Speed is an integral part of improving apps, services, and development in general. 

APIs automate tasks that would have to be programmed manually without APIs. The connection itself becomes more efficient because it does not rely on the tenacious, fast-typing labor of coders to use a pre-existing function. 

Innovation

Most would agree that APIs are one of the best avenues for digital transformation. Many of the examples you read above demonstrated exactly how APIs connect cloud apps and combine the different capabilities of several different technologies. 

Gone are the days where you needed a separate device to serve you for every little thing that you wanted to do. What are APIs, you ask? They’re tools of convenience and transformation. 

What Are the Types of APIs?

APIs, like almost everything else on this earth, are diverse. In the context of web development, there are roughly four different API types.

There are roughly four different API types.

REST

Representational State Transfer (REST) is definitely the most well-known web API. Hardly any web developer can get through a conversation in the modern age without it being mentioned at least once. 

Unlike other common APIs, REST is an architectural pattern, not a protocol. It is a set of constraints for creating web services, particularly interactive applications. REST uses a subset of HyperText Transfer Protocol (HTTP).

SOAP

Simple Object Access Protocol (SOAP) has been less popular since REST came around. While REST works with plain text, XML, HTML, and JSON, SOAP only uses Extensible Markup Language (XML) as a format to transfer data. 

SOAP is a means of structuring messages and other communication for web services. Ultimately, SOAP allows different operating systems to communicate with each other, like Linux and Windows

XML-RPC

XML-RPC is a type of remote procedure call (RPC) protocol. Its functionality permits programs to make procedure calls across a network.

The protocol utilizes XML to encode the call and HTTP for transport. XML-RPC is relatively old, first originating in 1998, and it's since been largely superseded by SOAP.

JSON-RPC

JSON-RPC is similar to XML-RPC, but this RPC uses JavaScript Object Notation (JSON) instead of XML. 

Conclusion

The average website visitor whose interest doesn’t go past the visible effects of front-end web development does not often inquire, “What are APIs?” or “How do APIs work?”.

Yet, everything that happens on the front-end looks sleek and behaves exceptionally due to back-end technologies like APIs. 

APIs have a great impact on how technology operates today and its impact will likely only grow in the future.

Whatever your next project is, no doubt APIs will be involved. Hire qualified integration developers with Trio to build APIs for your software development project!

Cordenne Brewster

Content Writer

About

A tech enthusiast whose ardor is best expressed through the written word.

Frequently Asked Questions

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An application programming interface (API) defines how two or more technologies communicate with one another.

APIs sit in the middle of the application and the server. The user asks the application to perform a task and the application uses the API to meet the demand. The API, in turn, must send a call to the server in order to make a formal request.

There are two principal use cases for APIs: internally and externally. For private or internal APIs, software development teams may use APIs for the operations that happen within their organization. External or open APIs are publicly accessible.