An API, which stands for application programming interface, is a set of protocols that enable different software components to communicate and transfer data. Developers use APIs to bridge the gaps between small, discrete chunks of code in order to create applications that are powerful, resilient, secure, and able to meet user needs. Even though you can't see them, APIs are everywhere—working continuously in the background to power the digital experiences that are essential to our modern lives.
Here, we'll give a high-level overview of the history of APIs and how they work before reviewing the different types of APIs and how they are used. We'll also discuss some common benefits and use cases for APIs—and offer a few real-world API examples that can help you get started.
In order to fully understand the role that APIs play in our lives, it's important to understand how they have evolved. APIs have been around for decades, with modern web APIs first taking shape in the early 2000s. The history of APIs since that period can be roughly broken down into the following five phases:
In the early 2000s, web APIs emerged as a new method for emerging startups to not only make products and services available online, but to also enable partners and third-party resellers to extend the reach of their platforms. This era of APIs was defined by Salesforce, eBay, and Amazon, and these companies continue to dominate the API playing field today.
A shift in the API landscape occurred in the mid-2000s, as a new group of companies—such as Flickr, Facebook, and Twitter—realized that APIs could change the way we share information with one another. While these APIs weren't as intrinsically linked to revenue as their commercial predecessors, they nevertheless provided significant value to their organizations. For instance, Facebook launched version 1.0 of its API in August of 2006, which allowed developers to access Facebook users' friends, photos, events, and profile information. This API played a crucial role in establishing Facebook as one of the most popular social networks in the world.
In 2006, Amazon introduced Amazon Simple Storage (S3), which marked yet another turning point in the history of APIs. S3 is a basic storage service in which resources are accessible via API and CLI, and its pay-as-you-go model provides a cost-efficient way for organizations to monetize digital assets in the online economy. Just six months later, Amazon released Amazon Elastic Compute (EC2), which enabled developers to use web APIs to deploy infrastructure that would power the next generation of applications. Both S3 and EC2 continue to play an essential role in application development today.
The world was introduced to Apple's iPhone and Google's Android in 2007. The ability to carry the web in our pockets radically changed how we live—and spurred a massive investment in mobile applications that are powered by APIs.
For instance, Twilio launched its API-as-a-product platform in 2007, which allowed developers to make and receive phone calls from any cloud application. Instagram then launched its photo-sharing iPhone application in October 2010, and it had one million users just three months later. Instagram did not initially provide an API, but it began work on one in early 2011 in response to user demand. These API-first companies played an essential role in creating the blueprint for how APIs are delivered today.
Around 2010, some developers began using APIs to connect everyday objects—such as cameras, thermostats, speakers, microphones, and sensors—to the cloud. This next generation of devices, which includes Fitbit, Nest, Alexa, can send and receive data, content, media, and other digital resources, further changing the way we interact with the world around us.