as four hexadecimal digits. This behavior is not specified by any RFC and has been rejected by the W3C. The 13th edition of ECMA-262 still includes an escape function that uses this syntax, which applies UTF-8 encoding to a string, then percent-escapes the resulting bytes. The application/x-www-form-urlencoded type When data that has been entered into HTML forms is submitted, the form field names and values are encoded and sent to the server in an HTTP request message using method GET or POST, or, historically, via email. The encoding used by default is based on an early version of the general URI percent-encoding rules, with a number of modifications such as newline normalization and replacing spaces with + instead of %20. The media type of data encoded this way is application/x-www-form-urlencoded, and it is currently defined in the HTML and XForms specifications. In addition, the CGI specification contains rules for how web servers decode data of this type and make it available to applications. When HTML form data is sent in an HTTP GET request, it is included in the query component of the request URI using the same syntax described above. When sent in an HTTP POST request or via email, the data is placed in the body of the message, and application/x-www-form-urlencoded is included in the message's Content-Type header. See also Internationalized Resource Identifier Punycode Binary-to-text encoding for a comparison of various encoding algorithms Shellcode References External links The following specifications all discuss and define reserved characters, unreserved characters, and percent-encoding, in some form or other: / STD 66 (plus errata), the current generic URI syntax specification. (obsolete, plus errata) and RFC 2732 (plus errata) together comprised the previous version of the generic URI syntax specification. (mostly obsolete) and RFC 1808 (obsolete), which define URLs. (obsolete), the first generic URI syntax specification. W3C Guidelines on Naming and Addressing: URIs, URLs, ... W3C explanation of UTF-8 in URIs W3C HTML form content types Various implementations: DevPal URL encoder – online developer tools that support URL encoding. Online URL encoder and decoder – encodes or decodes URLs within the browser. URL Encoder online – a website with various options to convert files or texts into URL-encoded format. URL Encode and Decode - Online – a website with various options to convert files or texts into URL-encoded format. URI schemes Internet Standards Binary-to-text encoding formats