URL, URI, and URN: What’s the Difference?

URLs, URIs, and URNs are all ways to refer to resources on the internet, but they are not the same. Each serves a unique purpose when it comes to identifying or locating a resource online. To make it easier to understand, let’s take a look at how each works.

1. URL (Uniform Resource Locator)

A URL is the most familiar term for most people. It’s what you type into your browser’s address bar to visit a website. In simple terms, a URL specifies the *location* of a resource on the web, and it can tell browsers where to retrieve a resource, like a webpage or image.

• Example: https://www.example.com/about-us
• Components: Protocol (https), Domain (www.example.com), Path (/about-us)

“Think of a URL as the address that helps you find a house. It points to a specific location where a resource resides.”

2. URI (Uniform Resource Identifier)

A URI is a broader concept that refers to anything that identifies a resource. URLs are a specific type of URI that provides the *location* of a resource. URIs, however, could simply name a resource without specifying where it is or how to get it.

Every URL is a URI, but not every URI is a URL. For instance, a URI could be a URN, which doesn’t necessarily give you a location, but instead uniquely *names* a resource.

• Example: https://www.example.com/about-us (URL)
• Example: urn:isbn:0451450523 (URN)

3. URN (Uniform Resource Name)

A URN is a type of URI that names a resource in a unique and persistent way. While it doesn’t provide the location of the resource, it acts as a unique identifier. For instance, in the case of books, a URN might be the ISBN (International Standard Book Number).

• Example: urn:isbn:0451450523
• Key Point: URNs are not actionable like URLs—they don’t provide a way to access the resource.

Conclusion

To summarize, a URL tells you where to find a resource, a URN tells you the name of the resource, and a URI is an umbrella term that can be either a URL or a URN. Understanding the differences between these terms can help you better navigate how web addresses and resources are managed.