Introduction to API

An API (Application Programming Interface) is a set of rules and protocols that

allows different software applications to communicate with each other. It serves

as an intermediary that enables two applications to talk to each other, defining

the methods and data formats that applications can use to request and exchange

information.

• •Interface: A contract between two applications
• •Abstraction: Hides complex implementation details
• •Standardization: Provides consistent ways to interact with a system
• •Reusability: Enables the same functionality to be used across multiple

There are several types of APIs, each with specific use cases:

Web APIs are accessible over the internet using the HTTP protocol. These

include:

• •RESTful APIs: Uses HTTP methods (GET, POST, PUT, DELETE) to perform

• •GraphQL APIs: Enables clients to request exactly the data they need
• •SOAP APIs: Uses XML for message format and can work with various protocols

These APIs provide a set of functions and procedures that developers can use to

build applications on a specific platform or framework.

These allow applications to interact with the underlying operating system,

accessing features like file systems, hardware, etc.

APIs are crucial in modern software development for several reasons:

• 1.Integration: They enable different systems to work together
• 2.Innovation: Developers can build on existing platforms
• 3.Efficiency: No need to build everything from scratch
• 4.Scalability: Systems can be built in a modular way

REST (Representational State Transfer) is an architectural style for designing

networked applications. RESTful APIs use HTTP requests to perform CRUD

operations (Create, Read, Update, Delete) on resources.

• •Statelessness: Each request contains all the information needed
• •Client-Server: Separation of concerns between client and server
• •Cacheable: Responses can be cached for efficiency
• •Uniform Interface: Resources are identified by URLs, manipulated through

The API economy refers to the business model where companies expose their

applications and data through APIs. This has transformed how businesses operate

and create value.

• •New Business Models: Monetizing data and services
• •Expanded Reach: Penetrating new markets through partnerships
• •Innovation: Enabling third-party developers to build on your platform
• •Internal Efficiency: Improving processes through better system integration

For this exercise, identify three applications you use regularly and consider:

• 1.What APIs might these applications be using?
• 2.How are these APIs enabling the application's functionality?
• 3.What would happen if these APIs were unavailable?

APIs are the foundation of modern software development, enabling integration

between systems, driving innovation, and creating new business opportunities. In

this course, we'll focus on building RESTful APIs using Express.js, but the

principles you learn will apply across different API styles and technologies.

• •Enable new business models (API economy)
• •Extend product capabilities
• •Increase development efficiency
• •Foster innovation through partnerships

• 1.Planning & Design
• 2.Development
• 3.Testing
• 4.Deployment
• 5.Monitoring & Maintenance
• 6.Retirement/Versioning

A diagram showing API as a bridge connecting different applications and systems.

Look for images that show the concept of APIs connecting mobile apps, web

services, and other systems.

• •[What is an API? (Application Programming Interface)](https://www.mulesoft.com/resources/api/what-is-an-api)
• •[APIs for Beginners - How to use an API](https://medium.com/quick-code/apis-for-beginners-how-to-use-an-api-74512953bd9)
• •[Understanding APIs: What They Are and How They Work](https://zapier.com/blog/what-are-apis/)
• •[RESTful API Design: 13 Best Practices to Make Your APIs Intuitive](https://medium.com/better-programming/restful-api-design-13-best-practices-to-make-your-apis-intuitive-8a97e47144eb)