Back to Glossary

API Defined

An API, or Application Programming Interface, is a type of software interface that offers a way for two or more programs to communicate with one another. In contrast to a user interface (UI), which is the connector between a user and a person, an API provides a way for software programs to interact, exchange information, and perform actions on each other's behalf.

An API allows information to be transferred between two applications through a request and response cycle. One application requests information from another, and the receiving application responds with the requested data. This is achieved through an API call or inquiry to your server. 

For example, when you use a social media app on your phone, it communicates with the social media company's servers through an API to retrieve data and perform actions like posting a message or sharing a photo.

How to Use it in a Sentence

An API facilitates the exchange of information between a client and a server.

Common API FAQs

APIs (Application Programming Interfaces) are used for a variety of purposes, including:

  1. Integrating different software applications: APIs allow different software applications to exchange data and interact with each other, making it possible to create integrated and interoperable systems — even if those systems are built using different programming languages.
  2. Accessing services and data: APIs provide a standardized way for developers to access and use services and data from other applications or platforms.
  3. Creating new applications: APIs provide building blocks that developers can use to create new applications more quickly and efficiently by reusing pre-developed code and functionality.
  4. Automating tasks: APIs can be used to automate repetitive or time-consuming tasks, such as data entry or file processing, by enabling applications to communicate with each other and exchange data automatically.
  5. Enabling mobile and web applications: APIs are essential for building mobile and web applications that rely on cloud-based services or data by providing a secure and controlled way to access and exchange information.

Overall, APIs are a key component of modern software development, enabling developers to create more powerful, flexible, and connected applications that can interact with each other and with a wide range of services and data sources.

An example of an API is the Google Maps API. Google Maps provides a set of APIs that allow developers to embed maps and location data into their applications. Using the Google Maps API, developers can add features like directions, place search, and location tracking to their applications.

Many popular online services and platforms offer APIs that allow developers to integrate their applications with the services provided by these platforms.

For instance, OneSignal offers the OneSingnal Server REST API, which makes it easy for app developers to message users and leverage a variety of pre-built messaging automation, targeting, and personalization features.

There are several types of APIs, including:

  1. REST APIs: Representational State Transfer (REST) APIs are a type of web-based API that use HTTP requests to retrieve and manipulate data. They are widely used and popular due to their simplicity and flexibility.
  2. SOAP APIs: Simple Object Access Protocol (SOAP) APIs are another type of web-based API that use the XML messaging protocol for exchanging data. SOAP APIs can be more complex to implement than REST APIs but offer advanced features like encryption and digital signatures.
  3. GraphQL APIs: GraphQL APIs are a newer type of API that use a query language to provide a more efficient way of retrieving and manipulating data. They are designed to be more flexible than REST APIs and allow developers to specify the exact data they need.
  4. Webhooks: Webhooks are an API that allows applications to receive real-time notifications when certain events occur. For example, a webhook can be used to notify an application when a new order is placed on an eCommerce website.
  5. RPC APIs: Remote Procedure Call (RPC) APIs are a type of API that allows an application to execute a function on a remote server as if it were a local function call. RPC APIs are commonly used in distributed computing environments.

These are some of the most common types of APIs, but there are other types as well, such as message-based APIs and event-driven APIs. The choice of API type depends on the application's requirements and the nature of the data being exchanged.

The main purpose of an API is to enable communication and data exchange between different software applications. APIs provide a standardized way for applications to interact with each other, allowing them to share data, perform actions, and integrate with each other's functionality.

APIs are designed to simplify the development process by providing pre-built functionalities and allowing developers to reuse code and services that have already been developed by others. This not only speeds up the development process but also helps to reduce costs and improve software quality.

Another important purpose of APIs is to provide a secure and controlled way for applications to access each other's data and functionality. APIs can be designed to enforce security protocols, authentication mechanisms, and access controls, ensuring that only authorized applications and users can access sensitive data and perform actions.

In simple terms, an API (Application Programming Interface) is a set of rules and protocols that enable different software applications to communicate and share data with each other.

Just like a waiter takes your order at a restaurant and communicates it to the chef in the kitchen, an API acts as an intermediary between different software applications, allowing them to exchange information and perform actions on each other's behalf.