URI和URL的区别

From RFC 3986:

A URI can be further classified as a locator, a name, or both. The term "Uniform Resource Locator" (URL) refers to the subset of URIs that, in addition to identifying a resource, provide a means of locating the resource by describing its primary access mechanism (e.g., its network "location"). The term "Uniform Resource Name" (URN) has been used historically to refer to both URIs under the "urn" scheme [RFC2141], which are required to remain globally unique and persistent even when the resource ceases to exist or becomes unav

ailable, and to any other URI with the properties of a name.

URI统一资源标识符 。至关于立了一个规矩：好比姓名的组成是  姓+名；

URL统一资源定位符   我根据这个规矩起了一个名字：李（姓）+小龙（名），注意这个李小龙是惟一的，世界上就一个叫李小龙的，你根据李小龙这个名字只能找到一我的。

URN 统一资源名