The difference between a URI and a URL, a URL and a URI

uri = uniform resource identifier.

url = uniform resource locator.

It usually consists of three parts:

1) the naming mechanism of the resource;

2) the hostname of the resource;

3) The name of the resource itself.

Note: The above three points are an explanation of the instance, not a necessary condition for the URI, the URI is just a concept, it doesn't matter how to implement it, as long as it uniquely identifies a resource.

A URL is a subset of a URI, a unified resource locator, and a URL can describe various information resources in a unified format, including files, server addresses, directories, etc. URLs are an implementation of the URI concept.

The difference between a URI and a URL.

Both the URI and the URL define what the resource is, but the URL also defines how the resource should be accessed. A URL is a specific URI that is a subset of the URI that not only uniquely identifies a resource, but also provides information to locate that resource. uri

is a semantic abstraction that can be absolute or relative, while a URL must provide enough information to locate it, be absolute.

URI: In computer terms, a Uniform Resource Identifier (URI) is a string of characters used to identify the name of an Internet resource. This type of identity allows users to interact with any resource, both local and Internet, through a specific protocol.

The URI is defined by a scheme that includes determining the syntax and associated protocols.

URL: The Uniform Resource Locator is a concise representation of the location and access method of a resource that can be obtained from the Internet, and is the address of a standard resource on the Internet. Every file on the internet has a unique URL that contains information that indicates the location of the file and what the browser should do with it.

It was originally invented by Tim Berners Lee as an address for the World Wide Web. It has now been developed by the World Wide Web Consortium as the Internet standard RFC1738.

URL includes URI and URN, URN is a unified resource name, URL is a unified resource locator, URI is a unified resource identifier, URN and URL are subsets of URI, in JSP's label technology, we can declare custom labels or Sun labels.

Custom label declaration statement:

Or: prefix is shorthanded, and these URIs are configured in the TLD file.

Still not very clear, keep looking:

A Uniform Resource Identifier (URI) is a compact string used to identify an abstract or physical resource. ”

A URI can be further classified as locator, name, or both. The term "uniform resource locator" (URL) is a subset of URIs that, in addition to identifying a resource, also provide a primary access mechanism for locating that resource (such as its network "location").

Then our omniscient Wikipedia digests this passage very well and describes it more vividly:

URIs can be divided into URLs, URNs, or something that has both locators and names. The urn acts like a person's name, and the URL is like a person's address. In other words:

The urn determines the identity of the thing, and the URL provides a way to find it. ”

From these descriptions we can draw some conclusions:

First of all, the URL is a type of URI (you can see it from that diagram). So if someone tells you that the URL is not the URI, he's wrong. But not all URIs are URLs, it's like butterflies can fly, but not all butterflies can fly, what do you make flies think!

What makes a URI a URL a URL is, of course, the "access mechanism" and "network location". http://or ftp://

The urn is part of the unique identity, which is a special name.

It seems to understand a little.,It seems that these are still quite controversial at present.,It's good to have a general understanding.。

url: Uniform Resource Locator That is, for example.

URI: generic resource identifier.

URI is a uniform resource identifier used to uniquely identify a resource.

The url is the Uniform Resource Locator, which is a specific URIThat is, the URL can be used to identify a resource, and it also indicates how to locate the resource.

Grammar. The URL consists of three parts: the resource type, the domain name of the host where the resource is stored, and the file name of the resource. It can also be thought of as consisting of 4 parts: protocol, host, port, and path.

The general syntax format of the URL is (optional with square brackets) :p rotocol : hostname[:

port] /path / parameters][?query]#fragment。

Differences between URIs, URLs, and URNs:

uri :uniform resource identifier;

url = uniform resource locator.

where the URL is a subset of the URI.

The URI is a generic resource identifier.

The URL is a Uniform Resource Locator.

For example. The url is.

The URI is: view

The URI is a generic resource identifier.

The URL is a Uniform Resource Locator.

For details, please refer to the following references.