The two most used HTTP methods are: GET and POST.
What is HTTP?
The Hypertext Transfer Protocol (HTTP) is designed to enable communications between clients and servers.
HTTP works as a request-response protocol between a client and server.
A web browser may be the client, and an application on a computer that hosts a web site may be the server.
Example: A client (browser) submits an HTTP request to the server; then the server returns a response to the client. The response contains status information about the request and may also contain the requested content.
Two HTTP Request Methods: GET and POST
Two commonly used methods for a request-response between a client and server are: GET and POST.
- GET - Requests data from a specified resource
- POST - Submits data to be processed to a specified resource
The GET Method
Note that the query string (name/value pairs) is sent in the URL of a GET request:
/test/demo_form.asp?name1=value1&name2=value2
Some other notes on GET requests:
- GET requests can be cached
- GET requests remain in the browser history
- GET requests can be bookmarked
- GET requests should never be used when dealing with sensitive data
- GET requests have length restrictions
- GET requests should be used only to retrieve data
The POST Method
Note that the query string (name/value pairs) is sent in the HTTP message body of a POST request:
POST /test/demo_form.asp HTTP/1.1
Host: w3ii.com
name1=value1&name2=value2
Some other notes on POST requests:
- POST requests are never cached
- POST requests do not remain in the browser history
- POST requests cannot be bookmarked
- POST requests have no restrictions on data length
Compare GET vs. POST
The following table compares the two HTTP methods: GET and POST.
| GET | POST | |
|---|---|---|
| BACK button/Reload | Harmless | Data will be re-submitted (the browser should alert the user that the data are about to be re-submitted) |
| Bookmarked | Can be bookmarked | Cannot be bookmarked |
| Cached | Can be cached | Not cached |
| Encoding type | application/x-www-form-urlencoded | application/x-www-form-urlencoded or multipart/form-data. Use multipart encoding for binary data |
| History | Parameters remain in browser history | Parameters are not saved in browser history |
| Restrictions on data length | Yes, when sending data, the GET method adds the data to the URL; and the length of a URL is limited (maximum URL length is 2048 characters) | No restrictions |
| Restrictions on data type | Only ASCII characters allowed | No restrictions. Binary data is also allowed |
| Security | GET is less secure compared to POST because data sent is part of the URL Never use GET when sending passwords or other sensitive information! |
POST is a little safer than GET because the parameters are not stored in browser history or in web server logs |
| Visibility | Data is visible to everyone in the URL | Data is not displayed in the URL |
Other HTTP Request Methods
The following table lists some other HTTP request methods:
| Method | Description |
|---|---|
| HEAD | Same as GET but returns only HTTP headers and no document body |
| PUT | Uploads a representation of the specified URI |
| DELETE | Deletes the specified resource |
| OPTIONS | Returns the HTTP methods that the server supports |
| CONNECT | Converts the request connection to a transparent TCP/IP tunnel |