Although in some cases a Uniform Resource Identifier (URI) and a Uniform Resource Locator (URL) may be used interchangeably, they are not the same.
Knowing the difference between a URI and a URL can make your website development easier. For example, you will be able to design a REST API more easily, as a URI or URL will identify every resource on the web.
In short, the main difference between a URI and a URL is that the former can be a name, a location or both, while the latter only provides the location of a resource.
In this article, we will explain in more detail the differences between a URI and a URL and their structure. In addition, we will include use cases for both a URI and a URL along with their pros and cons.
What is a URI?
A URI or Uniform Resource Identifier is a string of characters that generally identifies any web resource by a name, a location, or both. A Uniform Resource Locator (URL) and a Uniform Resource Name (URN) are the two types of URIs.
How to differentiate one from the other
See the following comparison table for a better understanding of the main differences between a URI and a URL.
| URI | URL |
|---|---|
| URI is an acronym for Uniform Resource Identifier. | URL is an acronym for Uniform Resource Locator. |
| URI is the superset of a URN and a URL. | URL is the subset of URI. |
| The URI identifies a resource and differentiates it from others by a name, a location, or both. | The URL identifies the web address or location of a unique resource. |
| The URI contains components such as schema, authority, path and query. | The URL has similar components to a URI, but its authority consists of a domain name and a port. |
| An example of a URI is ISBN 0-476-35557-4. | An example of a URL would be https://responsive-muse.com/. |
| URIs are often used in XML, tag library files and other files such as JSTL and XSTL. | The URL is mainly used to search for web pages on the Internet. |
| The URI scheme can be a protocol, a specification or a designation such as HTTP, file or data. | The URL scheme is a protocol, such as HTTP and HTTPS. |
Types of URIs
After knowing the main differences between a URI and a URL, let’s focus on the two types of URIs in detail.
Uniform Resource Name (URN)
A URN is a persistent, location-independent identifier that is intended to identify a resource permanently. This means that the resource remains valid even if its data is moved to another location.
To achieve this, a URN uses the schema to distinguish resources. For example, urn:isbn:0405999832 identifies a book by ISBN numbers.
Every Uniform Resource Name (URN) consists of at least three components:
- URN: each URN uses the prefix urn: schema specification.
- NID: refers to a namespace identifier that must be registered with the Internet Assigned Numbers Authority (IANA). It can include letters, digits or a hyphen followed by a colon.
- NSS: is a namespace-specific string that identifies the Internet resource. It can contain ASCII codes, digits, punctuation marks and special characters.
Uniform Resource Locators (URLs)
A URL specifies the method of obtaining a representation of the physical location by describing the primary access mechanism or its location on the network. The resources it attempts to locate can be a web page, a video, an image or any document published online.
Unlike a URN, this Internet resource identifier is not always persistent and location-independent as it specifies the path to the resource, which may change over time. In addition, a URL does not follow the URN scheme.
The main difference between the two identifiers is that a URN only specifies the name of a resource, whereas a URL needs the access technique or protocols to retrieve the location of the resource.
In short, all URLs are URIs, but not all URIs are URLs.
