What is the difference between a URL and a URI?

 The terms URL (Uniform Resource Locator) and URI (Uniform Resource Identifier) are closely related and often used interchangeably, but they have distinct meanings. Here's a detailed comparison between the two:

1. Definition:

   - URI: A URI is a string of characters that identifies a resource, such as a web page, a file, or a program. It provides a unique address or identifier for the resource.

   - URL: A URL is a specific type of URI that provides the means to access the identified

resource. It includes both the identifier and the method to retrieve or access the resource.

2. Components:

   - URI: A URI consists of two main parts: the scheme and the path. The scheme indicates the protocol or type of resource being accessed, such as "http://" for a web page or "ftp://" for a file transfer. The path specifies the location of the resource.

   - URL: A URL includes the same components as a URI but adds additional components, such as the hostname, port number, and query parameters. It provides a complete address for accessing a resource.

3. Purpose:

   - URI: The primary purpose of a URI is to identify a resource. It gives a unique name or identifier to the resource but may not specify the means to access it.

   - URL: A URL not only identifies the resource but also provides the necessary information to retrieve or access it. It specifies the protocol and the network location of the resource.

4. Usage:

   - URI: URIs are used in various contexts beyond the web, such as identifying files on a local file system or referencing resources in databases. They serve as a general concept for identifying resources.

   - URL: URLs are primarily used in web-based systems. They are commonly seen in web browsers' address bars, hyperlinks, and API endpoints. URLs are specific to web resources and provide a means to retrieve them.

5. Subset relationship:

   - URI: URIs encompass both URLs and URNs (Uniform Resource Names). URNs are a subset of URIs that provide a persistent name for a resource without specifying its location or access method.

   - URL: URLs are a specific type of URI that includes the network location and access method. Therefore, all URLs are URIs, but not all URIs are URLs.

In summary, a URI is a broader term that identifies a resource, while a URL is a specific type of URI that includes the means to access the resource. URIs can exist outside of web contexts, while URLs are primarily used in web-based systems.