REST API stands for Representational State Transfer Application Programming Interface. Let's break down what this means:

1. API (Application Programming Interface): An API is like a set of rules and tools that allows one software application to interact with another. It's a way for different programs to communicate and share information.
2. REST (Representational State Transfer): REST is a set of principles or rules for designing web services. These principles make it easier for different systems to communicate over the Internet.

Easy explanation:

Imagine you want to get information from a website. Instead of manually going to the website and copying the information, you can use a REST API. It's like a waiter in a restaurant:

• Resources: Think of each type of information on the website as a dish on the menu. Each dish is a "resource" (like a user profile or a list of products).
• HTTP Methods (GET, POST, PUT, DELETE): These are like actions you can ask the waiter to do. For example, you can "GET" a menu to see what's available, "POST" an order to add something new, "PUT" to update an order, and "DELETE" to remove something.
• Uniform Resource Identifier (URI): This is like the address of the restaurant. It tells the API where to find the information you want.

So, a REST API is like a waiter (API) in a restaurant (web service) that follows specific rules (REST principles) to help you get or send information (resources) using different actions (HTTP methods) at specific addresses (URIs). It's a way for different software systems to talk to each other over the internet in a structured and predictable manner.

Functions:

1. Communication between Services: In a cloud-based architecture, applications are often composed of multiple services that need to communicate with each other. RESTful APIs provide a standardized way for these services to exchange data and functionality.
2. Scalability: Cloud applications often need to scale dynamically based on demand. REST APIs enable the development of loosely coupled services, allowing them to be scaled independently. This flexibility is crucial in a cloud environment where resources can be added or removed as needed.
3. Interoperability: REST APIs are based on standard HTTP methods and data formats such as JSON or XML. This standardization promotes interoperability between different services and platforms, allowing components developed in different languages or running on different platforms to work seamlessly together.
4. Statelessness: RESTful services are stateless, meaning each request from a client contains all the information needed to fulfill that request. This makes it easier to distribute and scale services without worrying about the state of individual components.
5. Resource-Oriented Design: REST APIs are designed around the concept of resources, which can be any entity that can be identified and manipulated (e.g., data objects, services). This design principle provides a clear and consistent structure for organizing and accessing data within an application.
6. Uniform Interface: REST APIs provide a uniform interface between clients and servers. This consistency simplifies the development process and makes it easier for developers to understand and work with different parts of the application.
7. Security: REST APIs can be secured using standard authentication and authorization mechanisms, such as OAuth. This ensures that only authorized users or systems can access and interact with specific resources.
8. Flexibility and Evolvability: REST APIs support a wide range of data formats, and their statelessness and decoupled nature make it easier to introduce changes or updates to the application without affecting other components.
9. Client-Server Architecture: REST follows a client-server architecture, separating the concerns of the user interface and data storage. This division allows for better scalability and maintenance of both client-side and server-side components.
10. Easier Integration with Third-Party Services: Cloud applications often leverage third-party services for various functionalities. REST APIs, being widely adopted and supported, make it easier to integrate these external services into your application ecosystem.

REST API rules:

• Uniform Interface
• Client-server
• Stateless
• Cacheable
• Layered System
• Code on Demand (optional)

Tutorials:

What Is REST API? Examples And How To Use It: https://www.youtube.com/watch?v=-mN3VyJuCjM

What Is REST API? Examples And How To Use It - full course (3h) - https://www.youtube.com/watch?v=WXsD0ZgxjRw