What Is a URL? - Definition of Uniform Resource Locators

what is a URL

Web sites are found by their addresses on the World Wide Web. These addresses are known as URLs, or Uniform Resource Locators. Every website has a URL assigned to it, so both searchers and Web servers can find them quickly and easily.

The Parts of a URL

  • http://websearch.about.com/od/dailywebsearchtips/qt/dnt0526.htm is our example.
  • http://: "HTTP" stands for Hypertext Transfer (or Transport) Protocol, and is the identification technology used to communicate between Web servers and the users who access their information. In some URLs, you might see "HTTPS", which stands for "Hyper Text Transfer Protocol", a secure technology developed to keep sensitive transactions and information safe online. This first part of the URL indicates what protocol the URL will be using in order to deliver the information from the server to the user, and is in front of the domain name, separated by the "://".
  • domain name: The domain name is the textual representation of the IP address, used to identify a specific Web page or pages, and comes after the "://". For example, one of the IP addresses assigned to Facebook is; conversely, the domain name for Facebook's IP address is facebook.com. Every domain name has a top level domain. These are simple suffixes attached to the end of the domain name that indicates its place in the domain name hierarchy. Common top level domains are .com, org, .net, and .gov.
  • forward slash,then file name: path or directory on the computer to this file; which in our case is "od/dailywebsearchtips/qt". Think of a file cabinet, with folders assigned to specific topics, projects, or information. This identifying information is simply locating where these files can be found on the Web server, then displaying them for the end user.
  • name of file: name of file, usually ending in .html or .htm. The file name for this file is "dnt0526"; moving backwards through the URL we can deduce that the file lies in sub-directories called "qt", "dailywebsearchtips", and "od", is on the domain name "websearch.about.com", and is being delivered to us by the HTTP protocol.

    A URL is also known as a Web address.

    History of the URL

    In addition to creating HTML, the standard language used to create the vast majority of pages on the World Wide Web, and hyperlinks, the linked text connections between one Web page to the other, Tim Berners-Lee also originated the idea of Uniform Resource Locators, an organizational system that gave every Web page its own unique locational address online (you can read more about the Web's early history at How the Web Got Started).

    Different Kinds of URLs

    There are a wide variety of different kinds of URLs, as well as different terms to describe what a URL looks like. For example:

    Messy: This is a URL with a lot of garbled numbers and letters on it that makes little organizational sense, i.e., "http://www.example.com/woeiruwoei909305820580". Typically these URLs are computer-generated from programs creating thousands of Web pages on the same domain name.

    Dynamic: These are what the previous explanation of "messy URLs" really come from. Dynamic URLs are the end result of database queries that provide content output based on the result of that query. The URL ends up looking quite garbled, aka "messy", and often includes the following characters: ?, &, %, +, =, $. Dynamic URLs are often found as part of consumer-driven websites: shopping, travel, or anything that requires changing answers for many different user queries.

    Static: A static URL is the opposite of a dynamic URL. The URL is "hard-wired" into the Web page's HTML coding and will not change depending on what the user requests.

    Obfuscated: Obfuscated, or hidden, URLs are primarily used in phishing scams. Basically, a familiar URL is distorted in some way to make it seem legitimate.

    The user clicks on the obfuscated URL and is redirected to a malicious website.

    Clues That Web Addresses Can Give You

    There's a lot of information that you can glean from a simple URL, including:

    • what kind of server the Web page is hosted on
    • what kind of organization the Web page belongs to
    • where the Web page is located in the world
    • the names of the directories on the website

    By carefully looking at the different parts of any Web address, you can quickly determine quite a bit of useful information. In addition, by simply deleting parts of the URL, you can learn more about the website than what might be actually publicly accessible. For example:

    • http://www.widget.com/blog/music/: This points to a resource online, and the URL tells you that yes, indeed, it does point to a online resource. Let's go further back.
    • http://www.widget.com/blog/: By moving backwards in the URL from right to left, we we can see that we're now at the blog section of this publication.
    • http://www.widget.com: The home page of the website.

    The top level domain is the part of the URL that specifies what exactly that site is part of (institution, government, business, etc.). It's also easy to remember since it's always after the "." in the Web address, i.e., .com, .edu, and more.

    The acronym DNS stands for Domain Name System. A domain is a unique address on the Web that identifies one particular Web site. The Domain Name System is the unique set of domain name records; it transcribes the textual domain names (such as www.google.com) into their numeric equivalents, i.e., IP addresses, in order to make it easier for computer networks to find them via numerical computer languages/protocols.

    Are there different types of domains? 

    There are many different types of domains, including:

    • .com: commercial domains, now the largest presence on the Web
    • .org: organization, can be any type of organization
    • .gov: government agency, usually federal, but can be state
    • .edu: educational institution
    • .net: Internet Service Provider or network

    Web extensions, also known as top level domain names, are the part of the URL that specifies what exactly that site is part of (institution, government, business, country, etc.).

    The most well-known Web extensions are .com, .edu, .net, and .org.

    • .com: short for "commercial"; most popular Web extension
    • .org: short for "organization"; mostly non-profits, but can be used for any type of organization
    • .gov: short for "government"; usually a federal site, but also can indicate a state site
    • .edu: short for "educational"; most domains with an .edu extension are education-related
    • .net: short for "network"; many ISPs (Internet Service Provider) and networks use a .net extension.

    There are many more Web extensions than this, for example, each country also has a unique Web extension assigned to them (.uk for the United Kingdom, .fr for France, etc.). For a more specific breakdown of the various kinds of Web extensions, read What is a Top Level Domain Name?.

    Of course, this is a very simple example. However, by dissecting complex URLs one step at a time, quite a bit of information can be uncovered.

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