What exactly is an API?

If you want to learn about APIs, you’ve come to the right place! API stands for application programming interface. APIs are the little pieces of code that make it possible for digital devices, software applications, and data servers to talk with each other, and they’re the essential backbone of so many services we now rely on.

Digging deeper, an easy way to understand the definition of an API is to think about the applications that you use every day. In an internet-connected world, web and mobile applications are designed for humans to use, while APIs are designed for other digital systems and applications to use. Websites and APIs both do the same things, like return data, content, images, video, and other information. But APIs don’t return all the details that are needed to make things look pretty for the human eye—you only get the raw data and other machine-readable information needed behind the scenes to put the resources being delivered to work, with very little assistance from a human.

What is API integration?

“API integration” is a pretty common Google Search term, and we have good news. The whole reason APIs exist is to support integration. API integration is simply the connection between two (or more) applications, programs, services, or systems, using APIs. Applications use APIs to send and receive data and content between each other. Keep reading for a history of APIs, what they’re used for, examples, and more.

History of APIs

Web APIs got their start by putting the “commercial” in “.com,” powering commerce startups looking to change the way we do business on the web. They took advantage of this new medium to make products and services available to customers via a single website, and as they worked with partners, they sought to automate much of the commerce that was powering the web and included juggernauts like Salesforce, eBay, and Amazon. In 2004, a shift in the API landscape began to emerge as a new breed of API providers started to pop up, offering ways to share information with local and global social networks, led by the likes of Facebook and Twitter. With a strong start in commercial and social applications, APIs continued to grow as everything moved to the cloud, became much more mobile, and provided the foundation for next-generation devices. To get the full scoop on the history of APIs, check out this Postman blog post.

What are APIs used for?

What are APIs used for? Lots and lots and lots of things, including:

  • APIs power desktop applications.
  • APIs are behind most web applications.
  • APIs make mobile applications possible.
  • APIs are the integrations for no code solutions.
  • APIs connect devices to the internet.
  • APIs define the networks—or the information passed between applications, systems, and devices.
  • APIs even connect everyday things like automobiles, doorbells, dishwashers, and wearable devices.

Read more about what APIs are used for.

Why should you care about APIs?

Curious about why you should care about APIs? Here’s a very brief list:

  • APIs help you access the data you need to get your work done and do daily tasks—whether you’re a business user, a student, or using an application just for fun.
  • APIs make it possible to integrate different systems together, like Customer Relationship Management systems, databases, or even school learning management systems.
  • APIs help different departments, teams, and groups become more agile.
  • APIs help organizations, schools, government agencies, and nonprofits strengthen relationships with other organizations, research institutes, and agencies.

Need more reasons? Keep reading about why you should care about APIs.

How do APIs work?

APIs work by sharing data and information between applications, systems, and devices—making it possible for these things to talk with each other.

Sometimes the easiest way to think about APIs is to think about a metaphor, and a common scenario that a lot of folks use is that of the customer, a waiter, and a restaurant kitchen: A customer talks to the waiter and tells the waiter what she wants. The waiter takes down the order and communicates it to the kitchen. The kitchen does their work, creating the food, and then the waiter delivers the order back to the customer.

In this metaphor, a customer is like a user, who tells the waiter what she wants. The waiter is like an API, receiving the customer’s order and translating the order into easy-to-follow instructions that the kitchen then uses to fulfill that order—often following a specific set of codes, or input, that the kitchen easily recognizes. The kitchen is like a server that does the work of creating the order in the manner the customer wants it, hopefully! When the food is ready, the waiter picks up the order and delivers it to the customer.

Why use APIs: reasons to use APIs

What are the reasons to use APIs? Almost too many to count, but to truly answer this question, we asked thousands of developers and professionals why they choose to produce or consume APIs in our annual State of the API report. Here are their top answers:

  • Integration with internal and external systems
  • Adding or enhancing functionality of internal and external systems
  • Adding or enhancing functionality for customers
  • Speeding up software and system development
  • Reducing operating costs
  • Reducing software development costs
  • Improving software and system testing
  • Improving organizational security and governance
  • Enabling mobile application
  • Reducing outages and non-performing systems

The different kinds of APIs

There are many different types of APIs, and many different ways to categorize them. Here are some of the most common.

Internal vs. External vs. Partner APIs

One way to categorize APIs is by who has access to them:

  • Internal APIs are APIs that are private and only used by your team, department, company, or organization.
  • External APIs, also known as public APIs or open APIs (which is not to be confused with OpenAPI), are publicly available APIs that are available for anyone to use.
  • Partner APIs are private and shared only with specific, integration partners outside of your organization.
Architectural style

When it comes to API architecture, there are a number of styles—some newer, some older—and all have a place in the API ecosystem. Here are the most popular styles listed in order of how frequently they’re used:

Challenges of producing APIs and consuming APIs

When it comes to building APIs, there can be a number of challenges and obstacles that developers and teams face. Here, too, we sought insights from thousands of developers and professionals across the API industry to see what they think about the most common challenges:

  • Lack of time
  • Lack of knowledge
  • Lack of people
  • Complexity
  • Lack of documentation
  • Stakeholder prioritization
  • Lack of budget
  • Stakeholder expectations (unrealistic/unclear)
  • Leadership buy-in
  • Lack of tools
  • Team buy-in

Real-world examples of APIs 

Looking for real-world examples of APIs? Go no further than our directory of APIs, better known as the Postman API Network. The Postman API Network provides a central place for both API consumers and API producers to easily discover, explore, and share APIs.

You can find APIs from many popular providers in the Postman API Network, including the Twitter API, Imgur API, Okta API, and more.

Try APIs for yourself

Think you might be ready to try APIs for yourself? With the Postman API Platform, you can explore APIs, send requests, see what data is returned, and much, much more. Plus it’s totally free to get started.

What do you think about this topic? Tell us in a comment below.