Here are the most commonly used HTTP methods, explained with examples from a blog application:

1. GET

Purpose: Retrieve data from the server.
Example: Fetch a list of blog posts or a specific blog post.

Use Case:

Get all blog posts:

GET /api/posts

Response:

[
  {
    "id": 1,
    "title": "First Blog Post",
    "content": "This is my first post.",
    "author": "John Doe"
  },
  {
    "id": 2,
    "title": "Second Blog Post",
    "content": "This is my second post.",
    "author": "Jane Smith"
  }
]

Get a single blog post:

GET /api/posts/1

Response:

{
  "id": 1,
  "title": "First Blog Post",
  "content": "This is my first post.",
  "author": "John Doe"
}

2. POST

Purpose: Create new data on the server.
Example: Create a new blog post.

Use Case:

Create a new blog post:

POST /api/posts
Content-Type: application/json

{
  "title": "My New Blog Post",
  "content": "This is the content of my new blog post.",
  "author": "John Doe"
}

Response (Success):

{
  "id": 3,
  "title": "My New Blog Post",
  "content": "This is the content of my new blog post.",
  "author": "John Doe"
}

3. PUT

Purpose: Update an existing resource completely. Typically, the entire object must be sent with the update.
Example: Update the content of an existing blog post.

Use Case:

Update an existing blog post:

PUT /api/posts/1
Content-Type: application/json

{
  "title": "Updated Blog Post",
  "content": "This is the updated content of the blog post.",
  "author": "John Doe"
}

Response (Success):

{
  "id": 1,
  "title": "Updated Blog Post",
  "content": "This is the updated content of the blog post.",
  "author": "John Doe"
}

4. PATCH

Purpose: Update part of an existing resource, instead of replacing the entire resource (like PUT).
Example: Update only the title of a blog post.

Use Case:

Update the title of an existing blog post:

PATCH /api/posts/1
Content-Type: application/json

{
  "title": "Partially Updated Blog Post Title"
}

Response (Success):

{
  "id": 1,
  "title": "Partially Updated Blog Post Title",
  "content": "This is the content of the blog post.",
  "author": "John Doe"
}

5. DELETE

Purpose: Delete a resource from the server.
Example: Delete a specific blog post.

Use Case:

Delete a blog post:

DELETE /api/posts/1

Response (Success):

{
  "message": "Blog post deleted successfully."
}

6. OPTIONS

Purpose: Describe the communication options for the target resource. It's used to check which HTTP methods are supported by the server for a given resource.
Example: Check which HTTP methods are allowed on blog posts.

Use Case:

Request:
```
OPTIONS /api/posts
```
Response:
```
Allow: GET, POST, PUT, PATCH, DELETE
```

7. HEAD

Purpose: Similar to GET, but it only retrieves the headers of the response, not the body. Used to check if a resource exists or to retrieve meta-information like content type or length.
Example: Check if a blog post exists.

Use Case:

Request:
```
HEAD /api/posts/1
```

Response (headers only):

HTTP/1.1 200 OK
Content-Type: application/json
Content-Length: 345

Example Summary for Blog Application:

GET: Retrieve blog posts or details of a single blog post.
POST: Create a new blog post.
PUT: Fully update an existing blog post (e.g., changing both title and content).
PATCH: Partially update a blog post (e.g., change only the title).
DELETE: Remove a blog post.
OPTIONS: Check allowed HTTP methods.
HEAD: Check if a blog post exists without retrieving its content.

Each method serves a specific purpose, allowing RESTful APIs to be efficient and maintain the correct behavior across different actions.