✅ API & Web Services – Web Development Interview Q&A 🌐💬 

1️⃣ What is an API?
Answer:
API (Application Programming Interface) allows communication between two software systems. It defines how requests and responses should be formatted.

2️⃣ REST vs SOAP – What's the difference?
Answer: 
- REST: Lightweight, uses HTTP, supports JSON/XML 
- SOAP: Protocol-based, strict standards, uses XML 
REST is more common for modern web services.

3️⃣ What is RESTful API? 
Answer: 
An API that follows REST principles: 
- Uses HTTP methods (GET, POST, PUT, DELETE) 
- Stateless 
- Has structured endpoints 
- Supports caching

4️⃣ What are HTTP status codes?
Answer: 
Codes returned in response: 
- 200: OK 
- 201: Created 
- 400: Bad Request 
- 401: Unauthorized 
- 403: Forbidden 
- 404: Not Found 
- 500: Server Error

5️⃣ What is GraphQL?
Answer: 
A query language for APIs by Facebook. 
- Client defines the structure of the response 
- Single endpoint 
- Reduces over-fetching and under-fetching of data

6️⃣ What is CORS?
Answer:
Cross-Origin Resource Sharing – A security feature in browsers that blocks requests from other origins unless explicitly allowed by the server.

7️⃣ What is rate limiting?
Answer:
Limits the number of API requests a user/client can make within a time frame to prevent abuse.

8️⃣ What is an API key and how is it used?
Answer:
An API key is a token used to authenticate and authorize access to APIs. It’s passed in headers or query strings.

9️⃣ Difference between PUT and PATCH?
Answer:
- PUT: Replaces the entire resource 
- PATCH: Updates only specified fields

🔟 What is a webhook?
Answer:
A way for servers to send data automatically to other services (e.g., when an event happens). It’s push-based, unlike APIs which are pull-based.

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