About URL Encoding

URL encoding, also known as percent-encoding, is a mechanism for encoding information in a Uniform Resource Identifier (URI) under certain circumstances. Although it is known as URL encoding, it is also used more generally within the main Uniform Resource Identifier (URI) set, which includes both Uniform Resource Locator (URL) and Uniform Resource Name (URN).

What is URL Encoding?

URL encoding converts characters into a format that can be transmitted over the Internet. URLs can only be sent over the Internet using the ASCII character set. Since URLs often contain characters outside the ASCII set, the URL has to be converted into a valid ASCII format.

URL encoding replaces unsafe ASCII characters with a "%" followed by two hexadecimal digits. URLs cannot contain spaces. URL encoding normally replaces a space with a plus (+) sign or with %20.

When to Use URL Encoding

URL encoding is necessary in the following situations:

• Special Characters: When you need to include special characters in a URL, such as spaces, ampersands, question marks, etc.
• Non-ASCII Characters: When you need to include non-ASCII characters, such as accented characters or characters from non-Latin alphabets.
• Reserved Characters: When you need to include characters that have a special meaning in a URL, such as /, ?, #, etc.
• Query Parameters: When you need to include special characters in query parameters.

URL Encoding Standards

URL encoding follows the RFC 3986 standard, which defines the syntax of Uniform Resource Identifiers (URIs). According to this standard, the following characters are reserved and must be percent-encoded when they are used in a URI:

! * ' ( ) ; : @ & = + $ , / ? # [ ]

URL Encoding Examples

Here are some examples of URL encoding:

URL Encoding vs. HTML Encoding

URL encoding and HTML encoding (also known as HTML entity encoding) are two different encoding schemes used for different purposes:

• URL Encoding: Used to encode characters in a URL to ensure that the URL is properly formatted and can be correctly interpreted by web browsers and servers.
• HTML Encoding: Used to encode characters in HTML content to ensure that the characters are displayed correctly in a web browser and not interpreted as HTML tags or attributes.

URL Encoding in Different Programming Languages

Most programming languages provide built-in functions for URL encoding and decoding. Here are some examples:

• JavaScript: encodeURIComponent() and decodeURIComponent()
• Python: urllib.parse.quote() and urllib.parse.unquote()
• PHP: urlencode() and urldecode()
• Java: URLEncoder.encode() and URLDecoder.decode()