A URL identifies a resource by describing how and where it can be addressed. A typical absolute URL is

https://example.org:443/articles?id=42#comments

Main components

This URL contains:

scheme   https
host     example.org
port     443
path     /articles
query    id=42
fragment comments

The scheme determines the addressing or access convention. The host identifies the network name, the optional port selects an application endpoint, and the path identifies a resource within the authority's namespace.

Query and fragment

The query carries additional resource parameters according to application-defined semantics.

The fragment identifies a part or view of the retrieved resource for the client. It is not normally sent as part of an HTTP request to the server.

Relative URLs

A document can refer to another resource relative to its own URL:

images/logo.png
../index.html

The client resolves the relative reference against a base URL to obtain an absolute one.

URL versus resource contents

A URL identifies or locates a resource; it is not the resource itself. The representation returned for that URL can change over time or depend on request context.

URLs provide the addressing language that links documents and HTTP interactions into the Web.