URL (Uniform Resource Locator)

URL stands for Uniform Resource Locator: in simple terms, a URL is the web address of a specific resource on the Internet.

More precisely, it is the address of a resource available on a network, such as the Internet, that provides the means to retrieve a web page, image, file, video, or any other type of data and digital content. Each URL is unique, which means it leads to a specific location on the Internet.

The history of URLs begins with the advent of the World Wide Web in 1989, when Tim Berners-Lee and the CERN team developed the concept to facilitate access and navigation of online resources. Since then, URLs have become a fundamental standard for locating resources on the Internet and are essential to the architecture of the Web, and today they are also fundamental to SEO, as search engines use them to understand site structure and page content.

A URL consists of several parts, including the protocol (e.g., http or https), the domain (which may include a subdomain), and sometimes a path and query parameters that point to a specific page or resource within a website.

The URL structure is standardized to ensure that resources on the Internet can be reliably located and accessed by users and applications around the world, and is composed as follows:

1. Schema (or Protocol): Indicates the communication protocol used to access the resource. The most common are “HTTP” (Hypertext Transfer Protocol) and “HTTPS” (Hypertext Transfer Protocol Secure), which indicates an encrypted connection.
2. Schema Separator: Followed by the protocol, the schema separator is represented by “://”. It is used to separate the protocol from the rest of the URL.
3. Subdomain: Optional, it is a third part of the domain that can specify a particular subsection or service of the main site, such as “blog” in “blog.example.com.”
4. Domain: This is the unique name that identifies the website and usually reflects the name of the entity or service that runs it, such as “example” in “www.esempio.com.”
5. TLD (Top-Level Domain): This is the final extension of the domain, such as “.com,” “.org,” “.net,” often indicating the type or geographic origin of the resource.
6. Port: Optional, specifies the network port used to access the resource, such as “:80” for the standard HTTP port.
7. Path: Indicates the specific location of the resource within the server, structured into subfolders and files, as in “/page/subpage.”
8. Query Parameters: Optional, begin with a “?” and are followed by a series of key-value pairs separated by “&,” used to pass additional data to the server, as in “?key1=value1&key2=value2.”
9. Fragment (or Anchor): Optional, starts with a “#” and follows the path and/or query parameters. Indicates a specific location within a page, such as a title or section.

A complete example of a URL might be:

https://www.example.com:443/page/subpage?key1=value1&key2=value2#section

where “https” is the pattern, “www” is the subdomain, “example.com” is the domain, “443” is the port, “/page/subpage” is the path, “?key1=value1&key2=value2” are the query parameters, and “#section” is the snippet.