Response
An HTTP response is the data that a web server sends back to the client after responding to an HTTP request. It contains information about the processing of the request, such as the request status, metadata in headers, and often a body that includes the requested content or an error message.
When you interact with a web application, the server responds with an HTTP message indicating whether your request was successful or if there was an issue. The response includes a status code, which is a three-digit number, and a reason phrase, which provides a brief description of the result.
Status Line Structure
The first line of every HTTP response, known as the status line, consists of:
HTTP Version: Specifies which HTTP version is being used.
Status Code: A three-digit number indicating the outcome of the request.
Reason Phrase: A short, human-readable message explaining the status code.
Response Headers
In HTTP, response headers provide metadata about the server's response. These headers contain important information such as the type of content being sent, the server's identity, and caching directives. They help the client process the response and understand what to expect in the body.
Below are some essential response headers –
Content-Type
Specifies the media type of the response body.
text/html; charset=UTF-8
Content-Length
Indicates the size of the response body in bytes.
1024
Date
The date and time when the response was sent.
Wed, 08 Dec 2024 12:00:00 GMT
Server
Identifies the software used by the server.
Apache/2.4.41 (Ubuntu)
Cache-Control
Specifies the caching behavior of the response.
no-cache, no-store
Location
Used in redirection to specify the new URL of the resource.
https://navidnaf.com/new-page
Expires
Indicates when the response should be considered outdated.
Thu, 09 Dec 2024 12:00:00 GMT
Set-Cookie
Sends a cookie from the server to the client.
session_id=abc123; Path=/; HttpOnly
ETag
Provides a unique identifier for a version of the resource.
"1234567890"
X-Powered-By
Specifies the technology used by the server.
PHP/7.4.3
Response Body
The response body contains the main content of an HTTP response. In a successful request, the body typically includes the requested resource (such as HTML content, JSON data, or images). In an error response, the body may contain an error message or description. Responses like 204 No Content, or cases where no additional data is required, usually have an empty body. The format and structure of the body are determined by the Content-Type specified in the response headers.
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