What is an API?

What is an API?

An API or application programming interface is software that allows two applications to communicate. APIs also extract and share data within and across organizations. Businesses use APIs for various tasks:

• Third-party development: Developers utilize APIs to build custom applications or features that use data from other services, like embedding a video on a website.
• Marketing and analytics: APIs can access customer data for marketing campaigns and insights.
• Connecting internal systems: By facilitating information exchange between different departments, APIs can help avoid data silos.
• Enhancing security: APIs can grant access to security processes such as single-sign-on (SSO).

How do APIs work?

APIs share data between applications, systems, and devices through a request and response process. Here’s how it works:

1. API client

The API client starts the process by sending the request to the API server. The request can be triggered by entering a search term, clicking a button, or receiving and clicking on a notification from another application.

2. API request

An API request usually includes the following components:

• Endpoint: A dedicated URL to access a specific resource (ex. get an album’s details on Spotify using endpoint: https://api.spotify.com/v1/albums/{id}
• Method: The operation the client wants to perform, such as retrieving, creating, updating, and deleting data.
• Parameters: The variables instructing the API on processing (ex. the /articles endpoint of a blogging API has a “topic” parameter to access articles per topic.
• Request headers: Request headers provide additional details about the request, such as the content type or authentication credentials.
• Request body: The data needed to create or update a resource (ex. for an article in an app, the request body includes the article’s content, title, and author).

3. API server

The API client sends the request to the API server, to handle authentication, validate input data, and retrieve or change data.

4. API response

The API server responds to the client with the following components:

• Status code: Three-digit codes describing the outcome of an API request (i.e. 404 Not Found)
• Response headers: Used to provide additional information about the server’s response
• Response body: The data or content the client asked for or an error message if something went wrong

What are examples of APIs?

• Weather app: A weather app uses an API to connect with the weather bureau’s software, to retrieve daily weather data.
• Smart fridge: A smart fridge can connect to recipe apps or send notes to mobile phones through an API.
• Travel booking site: Travel booking sites use APIs to send users up-to-date information about availability from hotels and airlines.

Types of APIs

There are four different types of APIs used in web services: public, partner, private, and composite:

1. Public APIs is available to any developer or business.
2. A partner API is available only to authorized outside developers or API consumers (usually B2Bs).
3. Private APIs are only used within an enterprise to connect systems and data within the business.
4. Composite APIs combine two or more APIs to address complex API behaviors.