URL and URI
- URL Full name: Uniform Resource Locator (Uniform Resource Locator)
- URI full Name: Uniform Resource Identifier (Uniform Resource Identifier)
As an example of Https://github.com/favicon.ico, it is both a URL and a URI. The only way we specify access to it is through Url/uri. This includes access protocol HTTPS, Access path, resource name Favicon.ico. With the message provided by this link, we have direct access to the location of this resource. This is the role of URLs, URIs.
The URL is a subset of the URI. ===> Each URL is a URI, but not every URI is a URL.
The URI consists of two subclasses: Urn and URL. Where urn only names a resource but does not specify how to locate a resource (such as urn:isbn:0451450523) specifies a book's ISBN, which can be uniquely identified but not positioned.
▲. There are few urns used in the Internet, and almost all URIs are URLs.
Python crawler knowledge point--url and URI
