The difference between uri and url is simple to understand (what is the difference between uri and url)

Hello everyone, meet again, I'm your friend Quanstack Jun.

One, URI

<1>What is a URI

URI, Uniform Resource Identifier (URI), indicates that every available resource on the web, such as HTML documents, images, video clips, programs, etc., is identified by a URI.

<2>The structure of the URI

URI usually consists of three parts:

①Resource naming mechanism;

②The host name where the resource is stored;

③The name of the resource itself.

(Note: This is just the naming method of general URI resources. As long as the resource can be uniquely identified, it is called URI. The above three together are sufficient and unnecessary conditions for URI)

<3>URI example

For example: https://blog.csdn.net/qq_32595453/article/details/79516787

We can interpret it this way:

①This is a resource that can be accessed through https protocol,

②Located on the host blog.csdn.net,

③The resource can be uniquely identified by "/qq_32595453/article/details/79516787" (note that this is not necessarily a complete path)

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

Second, URL

URL is a subset of URI.It is the abbreviation of Uniform Resource Locator, translated as "Uniform Resource Locator".

In layman's terms, URL is a string describing information resources on the Internet, mainly used in various WWW client programs and server programs.

Using URL can use a unified format to describe various information resources, including files, server addresses and directories.A URL is an implementation of the URI concept.

The general format of URL is (with square brackets [] is optional):

protocol ://hostname[:port] / path / [;parameters][?query]#fragment

The format of the URL consists of three parts:

①The first part is the protocol (or service mode).

②The second part is the IP address of the host where the resource is stored (sometimes also includes the port number).

③The third part is the specific address of the host resource, such as directory and file name.

The first and second parts are separated by a "://" symbol,

The second and third parts are separated by a "/" symbol.

Parts 1 and 2 are indispensable, and part 3 can sometimes be omitted.

The difference between URI and URL

From the above example, you may think that URI and URL may be the same concept, but it is not. Both URI and URL define what a resource is, but URL also defines how to access the resource.A URL is a specific URI, which is a subset of URIs that not only uniquely identifies a resource, but also provides information for locating that resource.URI is a semantic abstraction, which can be absolute or relative, while URL must provide enough information to locate, it is absolute.

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Update: After reading everyone's questions, in fact, everyone can think that the uri is just a unique identification number, similar to your ID number, and the url is the ID address + name, so is it obvious~~

Update 2: In response to the questions of most students, what is actually tangled is what a URI is, why is it a URI and not a URL, in fact, it has been explained in the article, as long as it can uniquely identify a resource is the URI, the basis of the URIThe way to access its resources is given by the URL. This is the simplest summary. I hope it will be helpful to everyone. Good luck~~

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