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.

HTTP 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

The GET query string (name/value pairs) is sent in the URL of a GET request:

/test_route?name1=value1&name2=value2

The GET features are:

  • 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

The POST query string (name/value pairs) is sent in the HTTP message body of a POST request:

POST /test_route HTTP/1.1
Host: website.com
name1=value1&name2=value2

The POST features are:

  • 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

GET vs. POST

The following table compares the two HTTP methods: GET and POST.

 GETPOST
BACK button/ReloadHarmlessData will be re-submitted (the browser should alert the user that the data are about to be re-submitted)
BookmarkedCan be bookmarkedCannot be bookmarked
CachedCan be cachedNot cached
Encoding typeapplication/x-www-form-urlencodedapplication/x-www-form-urlencoded or multipart/form-data. Use multipart encoding for binary data
HistoryParameters remain in browser historyParameters are not saved in browser history
Restrictions on data lengthYes, 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 typeOnly ASCII characters allowedNo restrictions. Binary data is also allowed
SecurityGET 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
VisibilityData is visible to everyone in the URLData is not displayed in the URL