Rest APIs need no introduction in today's world as it is profoundly being used in .Net and other platforms for communication of different systems and provide a kind of encapsulation to users from the service provider's software internal architecture.

What is an API?

An API stands for Application Programming Interface. It is a set of rules and protocols that allows different software applications to communicate and interact with each other. It defines the methods and data formats that developers can use to access and manipulate the functionality and data of a particular software system or service.

In simpler terms, you can call it a bridge between unrelated software applications which may have architectural similarities or differences providing them the means to communicate with each other. It helps the developer, as when using an API the developer does not need to be familiar with the intricate details of the system the API provider has and use the API without having any dependency on the technologies used to develop the API.

What are some features of the API

• Standardized Interface: API provides a standardized interface that defines how the application should interact with the API which includes the information about the parameters to be passed the method to be used and the return type of the methods.

• Encapsulation: APIs encapsulate the underlying complexity of a system, allowing developers to access its functionality and data without needing to understand the internal workings of the system.

• Interoperability: API enables communication between different applications and systems so that they can work together seamlessly by adhering to common standards and protocols.

• Data Exchange: It enables the exchange of data between applications. As it defines data formats such as JSON or XML for representing and transmitting information.

These are some most important features of API. Now the most important question is mainly asked in the interview given below.

What is the definition of Rest?

REST stands for Representational State Transfer. It's an architectural style for designing networked applications. It provides the set of principles and guide to developing the web services and APIs for communication between different applications and systems over internet. REST, is a software architectural style that defines a set of constraints to be used when creating web services.

What are some action verbs / HTTP method used in REST API?

RESTful web services are characterized by their ability to interact with resources, represented as Uniform Resource Identifiers (URIs), through a set of operations, or HTTP methods, such as GET, POST, PUT, PATCH, and DELETE. The REST style aims to provide a scalable and flexible approach to designing web services, based on the principles of simplicity, uniformity, and statelessness. RESTful APIs are easy to use and understand, as they rely on common web standards and protocols, such as HTTP and JSON, to transmit data and metadata between clients and servers. Additionally, RESTful APIs can be easily integrated with other web services and applications, making them highly interoperable and reusable.

Various means of doing authentication in ASP.Net Web API?

API Key: A unique key must be provided for each client accessing this API. The client includes this key in API requests for authentication and access.

OAuth 2.0: OAuth 2.0 is an enterprise-level authorization protocol. It provides clients with an access point that allows them to access secure resources on behalf of the user. OAuth 2.0 supports various types of support, such as authorization codes, client certificates, and virtual support. [Most commonly used]

JSON Web Tokens (JWT): JWT is a compact and self-contained token format that can be used for authentication and authorization. It contains information about the user and can be digitally signed for authentication.[Most commonly used nowadays]

Basic authentication: This requires you to send a username and password in HTTP headers for each request. However, it is recommended that you use a secure connection (HTTPS) when using basic authentication.

Bearer Tokens: Bearer Tokens are used to authenticate API requests. The client includes the token in the Authorization header of the HTTP request, usually preceded by the word "Bearer".

Role-based access control (RBAC): In RBAC, roles and permissions for users or client applications must be defined. Users are assigned roles, and access to API resources is determined based on their assigned roles.

What is the difference between REST API and RESTful API?

Conclusion

The REST API has proven to be a powerful and versatile tool for developers to create web applications that are highly scalable and easily maintainable.RESTful services can provide an efficient and scalable solution for creating web applications that meet the demands of modern web development.