API - Application Programming Interface.

It is a set of rules and protocols that allows different software applications to communicate and interact with each other.

APIs define the methods and data formats that applications can use to request and exchange information.

Fundamentals of APIs:

1. Request-Response Model:

APIs follow a request-response model, where one application sends a request for specific information or functionality to another application, which then processes the request and sends back a response.

2. Standardized Communication:

APIs rely on standardised formats and protocols, such as HTTP, REST, or SOAP, to ensure consistent and efficient communication between applications.

3. Encapsulation of Functionality:

APIs encapsulate the functionality of an application, exposing specific operations or data to be accessed or manipulated by other applications.

4. Security and Access Control:

APIs often include mechanisms to authenticate and authorise access, ensuring that only authorized applications or users can interact with the exposed functionality.

Usages of APIs:

1. Integration:

APIs enable different applications or systems to integrate and share data, functionality, or services seamlessly. This integration allows for the exchange of information between applications, improving interoperability and enabling businesses to leverage multiple systems together.

2. Development of Third-Party Applications:

APIs are often exposed by companies to allow third-party developers to build applications that can interact with their services or platforms. These APIs empower developers to create innovative solutions that extend the functionality of existing systems or leverage data from external sources.

3. Service Composition:

APIs enable the composition of services from various providers, allowing developers to combine functionalities from multiple sources to create comprehensive applications or systems.

4. Mobile and Web Development:

APIs are essential for building mobile apps and web applications that rely on retrieving data from external sources, such as social media platforms, payment gateways, or mapping services.

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