HTTP/HTTPS methods (GET, POST, PUT, DELETE)

1. What is HTTP/HTTPS?

• HTTP (HyperText Transfer Protocol): Protocol used for communication between web browsers and servers.
• HTTPS (HTTP Secure): Secure version of HTTP that uses encryption (SSL/TLS).
• Purpose: Transmit data (requests and responses) over the web.

2. Why are HTTP/HTTPS Methods Important?

• Define how data is sent to/from servers.
• Enable CRUD operations:
• Create
• Read
• Update
• Delete

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3. HTTP Methods Overview

Method	Purpose	Common Use Cases
GET	Retrieve data	Fetch web pages, read records, search data.
POST	Send data	Submit forms, upload files, create resources.
PUT	Update/replace data	Update existing records, replace resources.
DELETE	Remove data	Delete records or resources from a server.

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4. Detailed Explanation of Methods

a) GET

• Purpose: Retrieve data from the server.
• Characteristics:
• Sends data in the URL (query parameters).
• Idempotent: Multiple GET requests produce the same result.
• No body content in the request.
• Example:

  GET /products?category=books HTTP/1.1
  Host: www.example.com

• Use Case: Search products, fetch user profiles, retrieve blog posts.

b) POST

• Purpose: Send data to the server to create new resources.
• Characteristics:
• Data sent in the body of the request.
• Non-idempotent: Repeated POST requests can create duplicate resources.
• Example:

  POST /register HTTP/1.1
  Host: www.example.com
  Content-Type: application/json

  {
    "username": "user123",
    "password": "pass123"
  }

• Use Case: User registration, file upload, form submission.

c) PUT

• Purpose: Update or replace existing data on the server.
• Characteristics:
• Sends data in the body of the request.
• Idempotent: Repeated PUT requests produce the same result.
• Example:

  PUT /profile/123 HTTP/1.1
  Host: www.example.com
  Content-Type: application/json

  {
    "name": "John Doe",
    "email": "john.doe@example.com"
  }

• Use Case: Updating user profiles, replacing configurations.

d) DELETE

• Purpose: Remove resources from the server.
• Characteristics:
• No body content in most cases.
• Idempotent: Repeated DELETE requests produce the same result.
• Example:

  DELETE /products/123 HTTP/1.1
  Host: www.example.com

• Use Case: Deleting user accounts, removing files, clearing data.

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5. Comparison Table

Feature	GET	POST	PUT	DELETE
Purpose	Retrieve data	Send/Create data	Update/Replace data	Remove data
Idempotent	Yes	No	Yes	Yes
Request Body	No	Yes	Yes	No
Common Use	Read operations	Create resources	Update operations	Delete records

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HTTP response codes:

Category	Code	Name	Meaning (Simplified)
Success	200	OK	Request succeeded, and the server returned the requested data.
	201	Created	A new resource has been successfully created.
	202	Accepted	Request accepted but not yet processed.
	204	No Content	Request succeeded, but there’s no content to return.
Redirection	301	Moved Permanently	Resource has permanently moved to a new URL.
	302	Found (Temporary Redirect)	Resource temporarily resides at a different URL.
	304	Not Modified	Resource hasn’t changed since the last request.
Client Error	400	Bad Request	The request is invalid or malformed.
	401	Unauthorized	Authentication is required or failed.
	403	Forbidden	The server understands the request but refuses to authorize it.
	404	Not Found	The resource could not be found on the server.
Server Error	500	Internal Server Error	A generic error occurred on the server.
	501	Not Implemented	The server doesn’t support the requested functionality.
	502	Bad Gateway	The server received an invalid response from an upstream server.
	503	Service Unavailable	The server is temporarily unavailable (e.g., maintenance or overload).

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6. Quick Revision Points

• GET: Fetch data – No body, data in URL.
• POST: Send data – Non-idempotent, body used for input.
• PUT: Update/replace data – Idempotent, uses body for input.
• DELETE: Remove data – Idempotent, typically no body.

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