The key difference between GET, POST, PUT, and DELETE lies in their purpose for interacting with web resources: GET retrieves data, POST creates new data, PUT updates or replaces data, and DELETE removes data.
These are the most common HTTP methods, also known as HTTP verbs, used to perform actions on resources identified by URLs on a web server. Understanding their distinct roles is fundamental for anyone working with web development or APIs.
Let's break down each method:
GET Method
The GET method is designed to retrieve data from a server. When you type a website address into your browser or click a link, your browser is typically sending a GET request.
- Purpose: To request and obtain data.
- Reference Inclusion: Used to retrieve data from a server.
- Characteristics:
- Safe: It doesn't change the state of the server. Multiple identical GET requests should have no side effects beyond retrieving data.
- Idempotent: Making the same GET request multiple times will produce the same result (retrieving the same data).
- Requests can be cached.
- Data is typically sent in the URL as query parameters (e.g.,
?id=123).
- Use Cases:
- Viewing a webpage.
- Searching for information.
- Fetching an image or file.
- Retrieving a list of items.
POST Method
The POST method is used to send data to the server to create a new resource or submit data for processing. When you fill out a form on a website (like signing up or submitting a comment) and click "submit", the browser often sends a POST request.
- Purpose: To send data to create or process a new resource.
- Reference Inclusion: Used to send data to the server to create a new resource.
- Characteristics:
- Not Safe: It can change the state of the server (by creating a new resource).
- Not Idempotent: Making the same POST request multiple times might result in multiple identical resources being created.
- Requests are generally not cached.
- Data is sent in the body of the request, making it suitable for sending larger amounts of data or sensitive information (though not encrypted by default).
- Use Cases:
- Submitting a contact form.
- Creating a new user account.
- Uploading a file.
- Sending data to an API endpoint to initiate an action.
PUT Method
The PUT method is used to update or replace an existing resource on the server. If you send a PUT request to a specific URL, you are essentially saying "replace whatever resource is at this URL with the data I'm providing".
- Purpose: To modify or completely replace a resource.
- Reference Inclusion: Used to update or replace an existing resource.
- Characteristics:
- Not Safe: It changes the state of the server.
- Idempotent: Making the same PUT request multiple times to the same URL with the same data will have the same effect as doing it once (the resource state will be the same).
- Requests are generally not cached.
- Data is sent in the body of the request.
- Use Cases:
- Updating a user's profile information.
- Replacing a document at a specific URL.
- Modifying the details of an existing product in an inventory.
DELETE Method
The DELETE method is used to remove a specific resource from the server.
- Purpose: To remove a resource.
- Reference Inclusion: Used to remove a resource from the server.
- Characteristics:
- Not Safe: It changes the state of the server (by deleting a resource).
- Idempotent: Making the same DELETE request multiple times to the same resource URL will have the same effect as doing it once (the resource will be gone after the first successful request). Subsequent requests will typically result in a "Not Found" response, but the end state (resource is gone) is the same.
- Requests are generally not cached.
- Requests typically don't have a body, though some implementations might allow it.
- Use Cases:
- Removing an item from a shopping cart.
- Deleting a blog post or comment.
- Removing a user account.
Summary Table
Here's a table summarizing the key differences:
| Feature | GET | POST | PUT | DELETE |
|---|---|---|---|---|
| Purpose | Retrieve data | Create new data or process data | Update or Replace existing data | Remove a resource |
| Idempotent? | Yes | No | Yes | Yes |
| Safe? | Yes | No | No | No |
| Data Location | URL Query Parameters | Request Body | Request Body | Typically URL (resource ID) |
| Cacheable? | Yes | No | No | No |
| Reference | Used to retrieve data from a server. | Used to send data to the server to create a new resource. | Used to update or replace an existing resource. | Used to remove a resource from the server. |
In essence, these four methods form the core actions (Read, Create, Update, Delete - often referred to as CRUD operations) you can perform on resources over the internet using the HTTP protocol. While POST can sometimes be used for updates or deletions, following the conventions of PUT and DELETE for those specific actions is considered best practice for building clear and predictable APIs.
