What is an Application Programming Interface (API)?

An Application Programming Interface, or API, is a set of programming instructions and standards for accessing a web-based software application or web tool. It is a set of protocols, routines, and tools for building software applications that specifies how software components should interact.

APIs allow software applications to communicate with each other, and enable developers to integrate different systems and services. For example, a weather website may use an API to access current weather data from a third-party weather service. This allows the website to display up-to-date weather information to its users without having to manage its own weather data.

APIs typically use a request-response model, where a request is sent to the API, and the API returns a response. The request contains information such as the endpoint (the specific data being requested), and any necessary authentication or authorization information. The response from the API includes the requested data.

APIs also play an important role in software development. Developers can use APIs to access existing functionality and data from other applications, rather than having to write new code from scratch. This saves time and resources and helps to promote innovation and collaboration in the development of new applications.

APIs come in various forms, including web-based APIs, which are available over the internet and can be accessed by any application with an internet connection, and local APIs, which are only available on a specific device or system.

Simplified Example

An Application Programming Interface, or API, is like a secret handshake between two friends. Just like how two friends can only play together if they know each other's secret handshake, different computer systems can only work together if they understand the API. This API allows them to communicate and share information in a way that makes sense to both systems. In the same way, when different trading platforms have an API, they can share information about trades and market conditions, making it easier for traders to move between different platforms without missing out on important information.

History of the Term "Application Programming Interface"

The term "Application Programming Interface" (API) is believed to have been coined in the early 1980s, though its exact origins are somewhat unclear. It was around this time that software development began to shift from monolithic applications to more modular systems. As a result, there was a growing need for a standardized way for different software components to communicate with each other.


REST API: An Application Programming Interface (API) refers to a set of protocols and routines for building and interacting with software applications. One example of an API is a REST API, which is a type of API that uses the Representational State Transfer (REST) architectural style. REST APIs allow developers to create, read, update, and delete resources using HTTP requests, such as GET, POST, PUT, and DELETE. REST APIs are commonly used to build web-based applications, and are widely used for building APIs for mobile apps, microservices, and other internet-based systems. REST APIs can be used to integrate different applications, allowing them to exchange data and perform actions on each other's behalf.

GraphQL API: Another example of an API is a GraphQL API, which is a newer and more flexible alternative to REST APIs. GraphQL APIs allow developers to make queries and mutations against a single endpoint, and can be used to fetch exactly the data that is needed by a client. GraphQL APIs provide a more efficient and powerful way of querying data, as compared to REST APIs, and allow developers to avoid over- or under-fetching of data. GraphQL APIs are commonly used in modern web and mobile applications, and are widely used in applications that require fast and flexible data access.

SOAP API: A third example of an API is a Simple Object Access Protocol (SOAP) API, which is an XML-based protocol for exchanging structured data over the internet. SOAP APIs are commonly used for building APIs for enterprise systems and services, and are widely used for integrating systems and services in business-to-business (B2B) scenarios. SOAP APIs provide a robust and secure way of exchanging data between systems, and allow for the exchange of complex data structures and data types. SOAP APIs are also widely used for building APIs that integrate with legacy systems, as they provide a stable and reliable way of exchanging data between systems that have been in use for many years.

  • Programmability: The ability of a technology, system, or device to be controlled and automated through the use of software programs and code.

  • Field Programmable Gate Array: An integrated circuit consisting of programmable logic components and programmable interconnects.