URL (address) definition

URL stands for Uniform Resource Locator or, in Spanish, Uniform Resource Locator. The URL is a way of organizing information on the web.

A URL is an address that allows access to a file or resource such as html, php, asp pages, or gif, jpg files, etc. It is a string of characters that identifies each resource available on the WWW.

What is my URL?

This is a question that our visitors often ask us a lot, probably motivated by some forms on the web that ask us to fill in a URL.

When they ask us for a URL in a web form, they usually ask us for the address of their own website or even the address of a user profile, such as Facebook (in the form www.facebook.com/your-name- username) or Instagram (www.instagram.com/username).

The reality is that we don’t always have a URL to put in a web form, so it is usually an optional field and can be left empty.

Other examples of URLs:

//

https://www.youtube.com/vevo

http://www.pagina.com/file.jpg

History and characteristics of URLs

URLs were first used by Tim Berners-Lee (the creator of the Web) in 1991 in order to create links between different pages on the WWW. Since 1994 the term URL has been incorporated into a more general concept, the URI, but URL is still used.

URLs essentially combine the idea of ​​domain names with the idea of ​​using a file path to identify a folder and file structure. So it’s similar to using a path like C:\Documents\Personal\myfile.txt on Windows, but with a few extra things at the beginning to help find the correct server on the Internet where that path exists and the protocol used to access the information. .

General form of a URL:

protocol://host/directory/file

HTTP protocol URLs are typical addresses to a web page, for example:

///Dictionary/dictionary.php

Difference between URL and web address

That simple URL is broken down into two main components: the scheme and the authority.

Many people think that a URL is just a web address, but it’s not that simple. A web address is a URL, but all URLs are not web addresses.

Other services that you can access on the Internet, such as FTP, or even locally, such as MAILTO, are also URLs.

The scheme part of a URL (those letters followed by a colon, like HTTP:) denotes the protocol with which an application (such as your web browser) and the server must communicate.

Web addresses are the most common URLs, but there are others. So you might see schematics like:

– Hypertext Transfer Protocol (HTTP): This is the underlying protocol of the web and determines what actions web servers and browsers should take in response to certain commands.

– HTTP Secure (HTTPS): This is a form of HTTP that works on top of a secure and encrypted layer for more secure information transport.

– File Transfer Protocol (FTP): This protocol is still often used to transfer files over the Internet.

In modern browsers, the scheme is not technically necessary as part of the URL. If you go to a website like «», your browser will automatically determine the correct protocol to use. Still, some other applications (and protocols) require the use of a scheme.

Authority

The authority part of a URL (which is preceded by two slashes, in our case ) is divided into several parts. Let’s start with a very simple URL, the kind that would take you to the home page of a website.

In this simple example, the entire «» part is called the hostname and resolves to an IP address. You can also type an IP address in your browser’s address bar instead of the hostname if you know it.

But, when parsing the hostname, it helps to read it backwards to understand what’s going on, so here are the components:

– Top level domain: in our example, «com.ar» is the top level domain. These are the highest levels in the Domain Name System (DNS) hierarchy that is used to translate IP addresses into plain language addresses that are easier for humans to remember.

These top-level domains are created and managed by the Internet Corporation for Assigned Names and Numbers (ICANN). The three most common top-level domains are .com, .net, and .gov. Most countries also have their own two-letter top-level domain, so you’ll see domains like .us (United States), .uk (United Kingdom), .ca (Canada), .ar (Argentina), . es (Spain), .br (Brazil), .mx (Mexico) and many others.

There are also some additional top level domains (such as .museum) sponsored and managed by private organizations. In addition to these, there are also some generic top-level domains (such as .club, .life and .news).

– Subdomain: Since DNS is a hierarchical system, the «www» and «» parts of our example URL are considered subdomains. The «www» portion is a subdomain of the «com.ar» top-level domain, and the «www» portion is a subdomain of the «» domain. That’s why you’ll often see a company with a registered name like «google.com» broken down into separate subdomains like «www.google.com», «news.google.com», «mail.google.com»…

That’s the most basic example of the authority section of a URL, but things can get more complicated. There are two other components that the authority section can contain:

– User Information: The authority section may also contain a username and password for the site you are accessing. It’s rare to see this structure in URLs today, but it can happen. If present, the user information part comes before the hostname and is followed by an @ sign. Therefore, you may see something like «//username:» if you include the user information.

– Port Number: Network devices use IP addresses to get information to the correct computer on a network. When that traffic arrives, a port number tells the computer the application for which that traffic is destined. The port number is another item you won’t often see when you browse the web, but you can see it in network applications (such as games) that require you to enter a URL. If the URL includes a port number, it comes after the hostname and is preceded by a colon. It will look something like this: «//www.example.com:8080».

Routes, queries and fragments in URLs

There are three additional parts of a URL that you can see after the authority part: paths, queries, and snippets. That’s how they work.

– Way or path

The authority section of a URL points your browser (or any application) to the correct server on a network. The following path, which works like a path on Windows, MacOS, or Linux, takes you to the correct folder or file on that server.

The path is preceded by a forward slash, and there is a slash between each directory and subdirectory, like this:

www.example.com/folder/subfolder/file.html

The last piece is the name of the file that is opened when you access the website. Even if you don’t see it in the address bar, that doesn’t mean it’s not there.

– Query

The query part of a URL is used to identify things that are not part of a strict path structure. In most cases, you will see them used when you perform a search or when a web page submits data through a form. The query part is preceded by a question mark and comes after the path (or after the hostname if a path is not included).

www.example.com/folder/subfolder/file.html?parameter=123 & parameter2=text

– Fragment

The final component of a URL that you can see is called a fragment. The snippet is preceded by a hash mark (#) and is used to indicate a specific location within a web page. When coding a web page, designers can create anchors for specific text such as headings. When the appropriate fragment is used at the end of a URL, your browser will load the page and then jump to that anchor within the web page.

Anchors and snippet URLs are often used to create tables of contents on web pages for easy navigation.

Bibliographic sources:
http://tools.ietf.org/html/rfc1738
https://www.howtogeek.com/356563/what-is-a-url-uniform-resource-locator/

Quote the definition:
Alegsa.com.ar (2018). URL Definition – ALEGSA 2018-09-04 url: https:///Dec/url.php