HTTP Request Headers

Accept:	Specify media types which are acceptable for response (e.g. pdf, gif, png, flash, etc.) Can also give ordered preferences using the `q` quality value: 1 is most preferred, 0 is least. `Accept: audio/*; q=0.2, audio/basic`
Accept-Charset:	Specify what charsets are acceptable for response. `Accept-Charset: iso-8859-5, unicode-1-1;q=0.8`
Accept-Encoding:	Restricts the content encodings that are acceptable. `Accept-Encoding: compress, gzip`
Accept-Language:	Restrict the language. `Accept-Language: da, en-gb;q=0.8, en;q=0.7`
Authorization:	Include the credentials (username and password) needed to authenticate with the server.
From:	Contains the email address of the human issuing the request. `From: president@whitehouse.gov`
Host:	Specifies the Internet host and port number of the resource being requested. `GET /pub/WWW/ HTTP/1.1 Host: www.w3.org`
If-Modified-Since:	Only return the document if it has been modified after the given date. `If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT`
User-Agent:	Specifies the user agent (web browser) being used. `Mozilla/4.0 (compatible; MSIE 5.5;Windows 98)`