URI, URL and URN

 

 

URI, URL and URN

• A Uniform Resource Identifier (URI)
  • is a string of characters that uniquely identify a name or a resource on the internet.URIs have two specializations known as Uniform Resource Locator (URL), and Uniform Resource Name (URN).
  • A URI identifies a resource by name, location, or both.
• A Uniform Resource Locator (URL)
  • is a type of URI that specifies not only a resource, but **how to reach it on the internet—like http://, ftp://, or mailto://.**
• A Uniform Resource Name (URN)
  • is a type of URI that uses the specific naming scheme of urn:—like urn:isbn:0-486-27557-4 or urn:isbn:0-395-36341-1.

So a URI or URN is like your name, and a URL is a specific subtype of URI that’s like your name combined with your address.

 

We’ve learned above that URIs include both URNs and URLs, but let’s break that into more detail.

1. A URI is an identifier of a specific resource. Examples: Books, Documents
2. A URL is special type of identifier that also tells you how to access it. Examples: HTTP, FTP, MAILTO
3. If the protocol (https, ftp, etc.) is either present or implied for a domain, you should call it a URL—even though it’s also a URI.

 

In other words, in 99% of everyday cases, you should use URL instead of URI because both are technically true but URL is more specific!

 

URL Structures

 

URLs have their own specific structure as well.

In that structure you have the following components:

• The Scheme, which is the protocol that you’re using to interact.
• The Authority, which is the target you’re accessing.
  • userinfo,
  • host,
  • and port.
• This breaks down into
• The Path, which is the resource you’re requesting on the host.
• The Query, which are the parameters being used within the web application.
• The Fragment, which is the target to jump to within a given page.

 

Schemes can include: HTTP, HTTPS, FTP, MAILTO, IRC, FILE, etc.