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HTML Uniform Resource Locators

HTML Uniform Resource Locators

A URL is another word for a web address.

A URL can be composed of words, such as “w3schools.com”, or an Internet Protocol (IP) address: 192.68.20.50. Most people enter the name of the website when surfing, because names are easier to remember than numbers.


URL – Uniform Resource Locator

Web browsers request pages from web servers by using a URL.

When you click on a link in an HTML page, an underlying <a> tag points to an address on the world wide web.

A Uniform Resource Locator (URL) is used to address a document (or other data) on the world wide web.

A web address, follows these syntax rules:

scheme://host.domain:port/path/filename

Explanation:

  • scheme – defines the type of Internet service. The most common type is http
  • host – defines the domain host (the default host for http is www)
  • domain – defines the Internet domain name, like w3schools.com
  • port – defines the port number at the host (the default port number for http is 80)
  • path – defines a path at the server (If omitted, the document must be stored at the root directory of the web site)
  • filename – defines the name of a document/resource

Common URL Schemes

The table below lists some common schemes:

Scheme Short for…. Which pages will the scheme be used for…
http HyperText Transfer Protocol Common web pages starts with http://. Not encrypted
https Secure HyperText Transfer Protocol Secure web pages. All information exchanged are encrypted
ftp File Transfer Protocol For downloading or uploading files to a website. Useful for domain maintenance
file A file on your computer

 


URL Encoding

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 converts characters into a format that can be transmitted over the Internet.

URL encoding replaces non ASCII characters with a “%” followed by two hexadecimal digits.

URLs cannot contain spaces. URL encoding normally replaces a space with a + sign.


URL Encoding Examples

Character URL-encoding
%80
£ %A3
© %A9
® %AE
À %C0
Á %C1
 %C2
à %C3
Ä %C4
Å %C5

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