URL vs. URI: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Updated on October 7, 2023

URL is a specific type of URI that provides the means to locate and retrieve a resource. URI is a string of characters used to identify a name or resource on the Internet, which can be classified as either a URL or URN.

Key Differences

URL, which stands for Uniform Resource Locator, always refers to a specific resource's address on the web. URI, or Uniform Resource Identifier, is a string of characters that identifies a particular resource. The URL can be perceived as a subset of URIs because every URL is a URI, but not every URI is a URL.

URLs contain information about how to fetch a resource from its location. In contrast, URI is a more generic term that encompasses URLs and is used to identify a resource without specifying the means to retrieve it. Thus, while the URL suggests both identity and location, URI is primarily concerned with identity.

URLs are always URIs, due to containing the practical details necessary for retrieval, such as HTTP, FTP, etc., which point to the resource location. Conversely, URIs might not be URLs because they might be URNs (Uniform Resource Names), which name a resource without providing its location.

URL implies accessibility, containing enough information to not only identify a resource but also interact with it, typically through HTTP or HTTPS protocols. URI, being a broader category, simply aims at identifying an entity, allowing a level of abstraction, and does not necessarily imply network accessibility.

URLs require more strict syntax due to their navigational utility, often specifying protocol, domain, path, and other components. In contrast, URI needs sufficient detail to uniquely identify the resources and may not provide the means to locate or retrieve it, having a more flexible syntax.

Comparison Chart

Definition

Locator of resources on the web

Identifier for resources, can be a URL or a URN

Type

A subset of URI

A superset, includes URL and URN

Usage

Specifies how to access a resource

Identifies a resource, doesn’t define access

Protocols

Must specify (e.g., HTTP, HTTPS)

No need to specify

Example

Https://www.example.com

Urn:isbn:0451450523

URL and URI Definitions

Url

A URL is a specific address used to access a resource on the internet.

You can visit our website by typing the URL www.example.com into your browser.

URI

A URI is a string that identifies any resource on the internet, which can be a URL or a URN.

The URI urn:isbn:123456789 identifies a book without specifying its location.

Url

URL contains protocol, domain name, path, and potentially other components to locate a web resource.

The URL http://example.com/path?query=term has multiple components indicating how to retrieve the resource.

URI

URI does not necessarily imply accessibility or location of the resource.

The URI might be a name or locator, depending on its specific type.

Url

URLs always imply the means to access a resource.

Use the URL ftp://files.example.com to access the FTP server and download files.

URI

URI allows a level of abstraction in identifying resources without demanding details on how to access them.

Using URI for identification allows system architects to separate identification and access mechanisms.

Url

A URL must specify a network protocol, like HTTP or FTP.

Ensure that the URL begins with HTTPS to establish a secure connection to the website.

URI

URIs encompass all means of resource identification, be it name-based or locator-based.

URIs serve as a general category for identifying resources in various namespaces.

Url

URL can be absolute, containing full access details, or relative, partial URLs used in conjunction with a base URL.

To link an internal page, use a relative URL like /contact-us, ensuring it connects from the site’s base URL.

URI

URI’s identification is not always tied to the resource’s current state or location.

A URI can remain consistent even if the resource it identifies moves or changes.

Url

An internet address (for example, http://www.hmhco.com/about-hmh), usually consisting of the access protocol (http), the domain name (hmhco.com), and optionally the path to a file or resource residing on the server where the domain name resides (about-hmh).

URI

Plural of urus

Url

The address of a web page on the world wide web

FAQs

What is the meaning of URI?

Uniform Resource Identifier.

Does a URL always have an associated protocol?

Yes, a URL includes a protocol, such as HTTP or FTP.

What is an example of a URL?

https://www.example.com is an example of a URL.

What does URL stand for?

Uniform Resource Locator.

What components are usually found in a URL?

Protocol, domain name, path, and possibly a query string and fragment.

Is a URL a URI?

Yes, a URL is a type of URI.

What is the purpose of a URI in computer science?

To identify resources uniquely, facilitating interaction and retrieval when necessary.

Are all URIs clickable links?

No, not all URIs are clickable links, as some URIs do not specify access mechanisms.

Do URLs always point to active webpages?

No, URLs point to resources, which may or may not be active webpages.

What's a real-world analogy for URL and URI?

A URI is like a person’s name, while a URL is like their address: the first identifies, the second locates and provides access.

Can you provide an example of a URI that is not a URL?

urn:isbn:123456789 is a URI (specifically a URN) but not a URL.

Can URLs and URIs be used interchangeably?

While often used interchangeably, technically, they have distinct definitions.

Can a URL be used to locate non-web resources?

Yes, URLs can locate FTP, email, database, and other resources.

Is the syntax of URL and URI always similar?

While similar, URIs may have varied syntax depending on whether they’re URLs or URNs.

Can a URI be a URL?

Yes, if it specifies the means to access the resource.

What protocol does a secure URL use?

A secure URL uses the HTTPS protocol.

Are URIs case-sensitive?

URIs are case-insensitive in the scheme and domain but may be case-sensitive in the path and query.

What is a URL path?

The part of the URL specifying the specific resource in the domain.

Why might a URI not specify how to retrieve a resource?

URIs can be designed to persistently identify a resource without tying it to a particular access path or method.

Do URIs always specify how to access a resource?

No, URIs identify a resource but don't necessarily specify how to access it.

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About Author

Written by

Harlon Moss

Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

Edited by

Aimie Carlson

Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.