What is an API?

What is an API?


API is a term that is frequently used and very important in software development. API stands for Application Programming Interface, but this name is often confusing and insufficient to understand what API is.

In this post, we will highlight all of the key API items to make this term clear to all parties who are interested.

What is an API?

Communication and data exchange are the foundations of everything. Systems have always needed to communicate with one another, but previously the percentage of system compatibility was very low. The communication between the systems was complicated because the most frequent changes in one system necessitated changes in the other systems due to their lack of compatibility. It was difficult to update and improve these systems due to these constraints.

API is designed to solve this problem by providing a means for software systems to communicate and exchange data. The API allows software systems to interact with one another more flexibly, making it easier to update and improve specific systems without affecting others.

The API provides a standardized method of communication and data exchange, which eliminates the problem of software system compatibility. This method allows for scalable software development while also encouraging innovation and integration with existing systems.

API components

An API is a collection of protocols, rules, and tools used to create software applications. As previously stated, an API enables different software systems to communicate and exchange data.

An API defines how software components will interact and be linked together, providing a set of agreed-upon rules for data exchange between software systems.

The API can be divided into several key components:

  • Endpoints
  • Methods
  • Request and Response
  • Data Format
  • Authentication and Authorization
  • Error Handling


The location of the API is technically referred to as an endpoint. It is a URL that points to the API server’s address.


Methods are actions that can be carried out using the API. GET, POST, PUT, DELETE, and other methods are the most commonly used.

Request and Response

The API employs a traditional client-server architecture, in which an API client sends a request to an API server, which receives the request, processes it, and returns a response to the client. The server’s response can be data that the client requested or a message that indicates whether or not the request was successful.

Data Format

APIs typically employ standardized data formats, such as JSON or XML. Data formats are used to encode data sent between the client and the server.

Authentication and Authorization

Data access via API typically necessitates authentication and authorization. This is typically accomplished by utilizing a key or token provided as part of the API request.

Error Handling

Because error handling is critical when developing software applications, APIs include error-handling mechanisms that allow the developer to control errors and exceptions that may occur during the request and response process.

Different types of APIs

APIs can be divided into several types based on their architecture and purpose.

There are several API types:

  • Open API
  • Internal API
  • Partner API
  • Composite API

Open API

This type of API, as the name implies, is available for use by developers and users with few restrictions. This type of API is also known as an external or public API. Typically, registration, app identification, or an API key are required for use.

Internal API

The internal API, in contrast to the external API, is hidden within the organization and can only be accessed by internal systems. Because of this approach, it is frequently referred to as a private API.

Partner API

This type of API is intended for partner companies to exchange specific functionalities. This type of API is only available to external developers to improve business-to-business (B2B) partnerships.

Composite API

By combining two or more different APIs into a single API, composite APIs are used to solve problems of complex system requirements and behavior.

How do APIs work?

APIs can work in a variety of ways, depending on the system’s implementation and requirements.

APIs are commonly used in the following ways:

  • GraphQL API
  • WebSocket API
  • Streaming API


The most popular and versatile web API that follows a stateless client-server architecture is a Representational State Transfer (REST) API. To manipulate data, it employs the Hypertext Transfer Protocol (HTTP) with the GET, POST, PUT, and DELETE methods. REST is a popular architectural style for developing web services that are widely used in modern web development.


Simple Object Access Protocol (SOAP) is a standard protocol for exchanging data in the implementation of web services. SOAP APIs encode messages between the client and the server using XML. Messages can be sent using a variety of lower-level protocols, including HTTP and SMTP. SOAP APIs are less flexible, which is why they were once more popular.


GraphQL is a Facebook-developed open-source data query and manipulation language for APIs. It is a more efficient, powerful, and adaptable REST alternative. Its advantage is that it allows clients to request only the information they require.


Remote Procedure Call (RPC) APIs allow systems to communicate as if they were calling local procedures, but the procedure call is executed on the remote system. So the client executes a function, or procedure, on the server, and the server returns the output to the client. When a client wants to run a remote procedure on a server, this method is used.

WebSocket API

The WebSocket API is a modern web API that sends data via JSON objects. It allows two-way communication between client and server applications. WebSocket API is more efficient than REST API because the server can send callback messages to connected clients.

Streaming API

A Streaming API provides instant access to data, such as stock prices or social media updates, as soon as it is available. Streaming APIs can be used to create real-time applications such as chat apps and news feeds.


We stated at the outset of the introduction that API is a commonly used and important term. APIs are critical tools for developing modern software systems. APIs were instrumental in connecting disparate software systems and enabling them to communicate with one another.

APIs provide developers with the ability to access and use the functionality of other systems and services. This approach enables developers to integrate multiple software applications and create novel solutions. APIs can be implemented in a variety of ways and are available in a variety of formats and protocols based on the needs of a particular use case.

They can be used for a variety of purposes, including data retrieval, system integration, and the development of new applications and services. APIs will continue to play an important role in the software development industry as demand for integration and automation grows, allowing developers to create innovative solutions and drive digital transformation.

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