What is the difference between a URI, a URL, and a URN?

To understand the differences between a URI, URL, and URN, let's break down each term:

1. URI (Uniform Resource Identifier): A URI is a string of characters that identifies a resource. It's a general concept that encompasses both URLs and URNs. A URI can be either a URL or a URN, or another type of resource identifier.

2. URL (Uniform Resource Locator): A URL is a specific type of URI that identifies a resource by its location, typically using a network protocol such as HTTP, FTP, or HTTPS. A URL specifies where a resource is located and how to access it. For example, https://www.example.com/index.html is a URL.

3. URN (Uniform Resource Name): A URN is a specific type of URI that identifies a resource by a unique name, rather than by its location. URNs are designed to persist and remain unique even if the resource changes location or disappears. For example, urn:isbn:978-0-393-31425-5 is a URN that identifies a book by its ISBN number.

Here's a summary of the key differences:

• URI: A general term for a string of characters that identifies a resource. It can be either a URL or a URN.
• URL: A URI that identifies a resource by its location and specifies how to access it using a network protocol.
• URN: A URI that identifies a resource by a unique name, rather than by its location.

In other words, a URL is a type of URI that specifies the location of a resource, while a URN is a type of URI that identifies a resource by a unique name. Both URLs and URNs are subsets of the more general URI concept.

It's important to note that the terms URI, URL, and URN are often used interchangeably, but they have distinct meanings and purposes. Understanding these differences can be helpful when working with web technologies and resource identification.

The terms URI, URL, and URN can be a bit confusing as they are related concepts. Here's a breakdown of the differences between them:

URI (Uniform Resource Identifier):

• A URI is a string of characters that identifies a resource.
• It is a superset that includes both URLs and URNs.
• The syntax of a URI is defined in RFC 3986.
• Examples of URIs:
  • https://www.example.com/page.html (URL)
  • urn:isbn:0451450523 (URN)
  • mailto:john@example.com
  • ftp://ftp.example.com/file.txt

URL (Uniform Resource Locator):

• A URL is a subset of URI that identifies a resource and specifies the means of accessing it.
• It indicates the location of a resource on a network and the protocol used to access it.
• A URL typically consists of a scheme (protocol), authority (domain), path, and optional query parameters and fragment identifier.
• Examples of URLs:
  • https://www.example.com/page.html
  • ftp://ftp.example.com/file.txt
  • mailto:john@example.com

URN (Uniform Resource Name):

• A URN is a subset of URI that provides a unique and persistent name for a resource.
• It identifies a resource by its name in a given namespace, regardless of its location or how it can be accessed.
• URNs are often used to identify resources that may not have a direct network location, such as books, documents, or abstract concepts.
• Examples of URNs:
  • urn:isbn:0451450523 (identifies a book by its ISBN)
  • urn:uuid:6e8bc430-9c3a-11d9-9669-0800200c9a66 (a UUID URN)

In summary:

• URI is the broader concept that encompasses both URLs and URNs.
• URL is a subset of URI that identifies a resource and specifies how to access it over a network.
• URN is a subset of URI that provides a unique and persistent name for a resource, regardless of its location or access method.

It's worth noting that in common usage, the terms "URI" and "URL" are often used interchangeably, especially when referring to web addresses. However, technically, a URL is a specific type of URI.

I hope this clarifies the differences between URI, URL, and URN! Let me know if you have any further questions.

The terms URI, URL, and URN are related but have distinct meanings in the context of web resources and addressing. Let's break them down:

URI (Uniform Resource Identifier) A URI is a string of characters that identifies a resource on the internet or any other system. It provides a way to locate and identify resources, whether they are web pages, files, services, or anything else. A URI is the most general and broad term among the three.

URL (Uniform Resource Locator) A URL is a specific type of URI that identifies the location of a resource on the internet. It specifies the protocol to be used to access the resource (e.g., HTTP, HTTPS, FTP), the domain name or IP address, and the path to the resource within the server's directory structure. URLs are primarily used to locate and retrieve resources on the World Wide Web.

Example of a URL: https://www.example.com/path/to/resource.html

URN (Uniform Resource Name) A URN is another type of URI that provides a way to identify a resource by name in a particular namespace, rather than by its location. URNs are designed to provide persistent, location-independent identifiers for resources. They are often used in scenarios where resources need to be identified uniquely, regardless of their current location or how they are accessed.

Example of a URN: urn:isbn:0451450523 (identifying a book by its ISBN)

In summary:

• URI is the umbrella term that encompasses both URLs and URNs, as well as other types of identifiers.
• URL is a specific type of URI that provides the location of a resource on the internet, including the protocol, domain, and path.
• URN is another type of URI that provides a persistent, location-independent name for a resource within a specific namespace.

URLs are the most commonly used type of URI on the web, as they allow browsers and other clients to locate and retrieve resources from servers. URNs are less commonly used but can be useful in scenarios where resources need to be identified uniquely, regardless of their location or access method.

Sure, here's the difference between a URI, URL, and URN:

Uniform Resource Identifier (URI)

• The URI is the standardized syntax for identifying resources on the web.
• It consists of four main parts: scheme, host, path, and query.
• URI is used in various protocols, such as HTTP, HTTPS, FTP, and mailto.

Uniform Resource Locator (URL)

• The URL is a type of URI that specifically identifies resources on the World Wide Web.
• It includes the scheme, host, path, and optional query parameters.
• URL is commonly used to access websites and web resources.

Uniform Resource Name (URN)

• The URN is a more abstract identifier used to uniquely identify resources across different protocols and systems.
• It is primarily used in electronic resource descriptions (ERDs) for the Internationalization Resource Identifier (IRI) framework.
• URNs can be used to identify resources regardless of their specific protocol or implementation.

Key Differences:

• URI: Identifies resources on the web and other systems.
• URL: Special type of URI used for web resources.
• URN: Abstract identifier for resources, not specific to a particular protocol.

Examples:

• URI: urn:uuid:1234abcd-5678-9bcd-a1bd-8a42a0f00000
• URL: http://example.com/path/to/resource

Additional Notes:

• URLs are a subset of URIs.
• URIs are more widely used than URNs.
• URNs are used when there is a need to identify resources in a more abstract way.

Sure, I'd be happy to explain the difference between a URI, a URL, and a URN! These are all concepts related to identifying resources on the internet, but they serve different purposes and have different formats.

URI (Uniform Resource Identifier)

A URI is the most general of the three concepts. It is a string of characters that uniquely identifies a resource. A URI can be either a URL or a URN, but it doesn't have to be either. The format for a URI is defined in RFC 3986. Here's an example of a URI:

mailto:jane@example.com

In this example, "mailto:" is the scheme, and "jane@example.com" is the opaque part of the URI that identifies a specific email address.

URL (Uniform Resource Locator)

A URL is a type of URI that provides the means of locating a resource by describing its primary access mechanism (e.g., its network "location"). The format for a URL is also defined in RFC 3986. Here's an example of a URL:

https://www.example.com/index.html

In this example, "https" is the scheme, "www.example.com" is the host, and "/index.html" is the path to the resource.

URN (Uniform Resource Name)

A URN is a type of URI that serves as a persistent, location-independent name for a resource. The format for a URN is defined in RFC 2141. Here's an example of a URN:

urn:isbn:0-486-27557-4

In this example, "urn" is the scheme, "isbn" is the namespace identifier, and "0-486-27557-4" is the name of the resource (an ISBN number for a specific book).

To summarize, a URI is a generic identifier for a resource, a URL is a type of URI that provides a location for a resource, and a URN is a type of URI that provides a persistent name for a resource.

A URI (Uniform Resource Identifier) is a string used to identify a resource on the web. It consists of three components: the scheme, which specifies the protocol to be used; the authority, which provides access to the server; and the path, which indicates the location of the resource on the server.

A URL (Uniform Resource Locator) is a specific type of URI that refers to a web page or other document. It includes additional information, such as the protocol being used to retrieve the resource and any parameters required by the server. For example, a URL might be used to retrieve an HTML document from a server, while a URI would identify the resource but not necessarily specify how it was retrieved.

A URN (Uniform Resource Name) is a string that identifies a particular instance of a resource within a given namespace. It does not include any information about where the resource can be found or how to access it. A URN provides a unique identifier for the resource, but it does not provide any information about the protocol to use or how to retrieve the resource.

In summary: A URL is a specific type of URI that refers to a web page or other document and includes additional information such as the protocol being used to retrieve the resource and any parameters required by the server. A URN provides a unique identifier for the resource within a given namespace but does not provide any information about where it can be found or how to access it.

URI (Uniform Resource Identifier)

A URI is a string of characters used to identify a resource. It can be used to locate a resource on the Internet, such as a web page, an image, or a video. URIs are often used in conjunction with HTTP, the protocol used to transfer data over the Internet.

URL (Uniform Resource Locator)

A URL is a type of URI that specifies the location of a resource on the Internet. It includes the protocol (such as HTTP or HTTPS), the domain name (such as www.example.com), and the path to the resource (such as /index.html). URLs are used to locate resources on the web, and they can also be used to link to resources in other documents, such as web pages and emails.

URN (Uniform Resource Name)

A URN is a type of URI that identifies a resource by its name, rather than its location. URNs are typically used to identify resources that are not located on the Internet, such as books, articles, and patents. URNs can also be used to identify resources that are located on the Internet, but that may change location over time.

Summary

The following table summarizes the key differences between URIs, URLs, and URNs:

Additional Information

For more information on URIs, URLs, and URNs, please refer to the following resources:

• RFC 3986 - Uniform Resource Identifier (URI): Generic Syntax
• MDN Web Docs: URIs
• MDN Web Docs: URLs
• MDN Web Docs: URNs

URI, URL, and URN are related but distinct concepts in the world of web resources.

URI (Uniform Resource Identifier)

• A URI is a unique address that identifies a specific resource on the web.
• It consists of a scheme (e.g., "http", "https"), followed by a resource path (e.g., "example.com/path/to/resource").
• URIs are typically used by browsers and other web applications to communicate with servers and retrieve the requested content.

URL (Uniform Resource Locator)

• An URL is a address that takes you directly to a specific resource on the web.
• It is a URI preceded by the "HTTP" protocol (e.g., "HTTP://example.com/path/to/resource").
• URLs are often easier to remember and type than URIs, making them commonly used in web addresses.

URN (Uniform Resource Name)

• A URN is an alternative name for a resource, typically used by libraries and other citation management systems.
• It is a string of characters that represents a specific resource identifier within a library's catalog.
• URNs are used when you need to reference a resource in a way that is not accessible through a URI.

In summary:

Remember that URIs and URLs are essentially the same, but URNs are used internally by specific systems for resource management.

From RFC 3986:

A URI can be further classified as a locator, a name, or both. The term "Uniform Resource Locator" (URL) refers to the subset of URIs that, in addition to identifying a resource, provide a means of locating the resource by describing its primary access mechanism (e.g., its network "location"). The term "Uniform Resource Name" (URN) has been used historically to refer to both URIs under the "urn" scheme [RFC2141], which are required to remain globally unique and persistent even when the resource ceases to exist or becomes unavailable, and to any other URI with the properties of a name. So all URLs are URIs, and all URNs are URIs - but URNs and URLs are different, so you can't say that all URIs are URLs. If you haven't already read Roger Pate's answer, I'd advise doing so as well.

A Uniform Resource Identifier (URI), A Uniform Resource Locator (URL), and A Uniform Resource Name (URN) are related concepts used in identifying resources on the web, but they serve different purposes.

A URI is the most general term for a string of characters used to identify a resource. It includes both URLs and URNs.

A URL is a specific type of URI that identifies the location of a resource. The "location" can refer to a file on a server, a web page, or any other resource accessible over the network. A URL has a format that includes a protocol (such as "http:" or "ftp:"), a domain name or IP address, and an optional path to a particular resource. For example, "http://www.example.com/path/to/resource" is a valid URL.

A URN is also a specific type of URI that identifies a resource by its name, rather than its location. A URN doesn't contain any location information and is designed to be persistent regardless of the resource's physical or logical address. URNs use a syntax based on a scheme followed by a namespace identifier, and optionally a name within that namespace. For example, "urn:iso:std:ISO-4801:2009" is an example of a URN without any specific resource name.

So in summary, URLs tell where to find the resources, while URNs give unique identifiers for resources. A URI can be both a URL and a URN depending on how it is used.

Sure, I'd be happy to help! A URL (Uniform Resource Locator) is the address or location of a web resource on the internet, such as a web page, image or video. A URI (Uniform Resource Name) is used for describing any kind of information resource in an unambiguous way, which can include a wide range of objects beyond just websites - from PDF files and Excel spreadsheets to file shares and databases. In contrast, a URN (Universal Reference Name) is a standard notation that specifies a unique identifier for an entity such as a resource or document. This makes it easier to share and identify resources across different systems without needing to worry about how they are identified locally. Essentially, URLs and URIs are similar in that both specify the location of a specific object online - but URNs take this one step further by providing a universal identification code.

A URI is a Uniform Resource Identifier which provides an absolute reference to the resource. It includes all the components of both URLs (Uniform Resource Locators) and URNs (Uniform Resource Names).

URL is commonly used by web browsers for locating specific content on the Internet, like pages or files. In a URL, "http" indicates the protocol for locating resources on the world wide web.

URN stands for Uniform Resource Name, which represents names in a hierarchical naming scheme. It provides a name for the resource by identification of the resource itself rather than locator information. An example of URNs could include ISBN numbers in a book (the unique identifier).

So, URL and URI are related but not identical. They are both types of Uniform Resource Identifier/Locators which includes everything needed to access or reference resources on the internet; they are absolute references to identify a resource directly by name. URNs don't give specific location information, they provide unique names for identifying resources, while URL does.

URI and URL; however, , so every URL is also a URI, but there are URIs which are not URLs.

Examples

- This is my name, which is an identifier. It is like a URI, but cannot be a URL, as it tells you nothing about my location or how to contact me.

In this case it also happens to identify at least 5 other people in the USA alone.

This is a locator, which is an identifier for that physical location. It is like both a URL and URI (since all URLs are URIs), and also identifies me indirectly as "resident of..". In this case it uniquely identifies me, but that would change if I get a roommate. I say "like" because these examples do not follow the required syntax.

Popular confusion

From Wikipedia:

In computing, a Uniform Resource Locator (URL) is a subset of the Uniform Resource Identifier (URI) that specifies where an identified resource is available and the mechanism for retrieving it. , ... [emphasis mine] Because of this common confusion, many products and documentation incorrectly use one term instead of the other, assign their own distinction, or use them synonymously.

URNs

My name, Roger Pate, could be like a URN (Uniform Resource Name), except those are much more regulated and intended to be unique across space and time. Because I currently share this name with other people, it's not globally unique and would not be appropriate as a URN. However, even if no other family used this name, I'm named after my paternal grandfather, so it still wouldn't be unique across time. And even if wasn't the case, the possibility of naming my descendants after me make this unsuitable as a URN. URNs are different from URLs in this rigid uniqueness constraint, even though they both share the syntax of URIs.

A URI (Uniform Resource Identifier) represents a name for an entity or resource over a network. A URL (Uniform Resource Locator) is a string of text that defines a location in the Internet. A URN (Uniform Resource Name) represents an abstract name used to uniquely identify a resource on the Internet. In summary, the main difference between URI, URL, and URN is their purpose and functionality.