In computing, a uniform resource locator (URL) is a specific character string that constitutes a reference to an Internet resource.
A URL is technically a type of uniform resource identifier (URI) but in many technical documents and verbal discussions, URL is often used as a synonym for URI.
URL (Uniform Resource Locator, previously Universal Resource Locator) is the unique address for a file that is accessible on the Internet. A common way to get to a Web site is to enter the URL of its home page file in your Web browser's address line. However, any file within that Web site can also be specified with a URL. Such a file might be any Web (HTML) page other than the home page, an image file, or a program such as a common gateway interface application or Java applet. The URL contains the name of the protocol to be used to access the file resource, a domain name that identifies a specific computer on the Internet, and a pathname, a hierarchical description that specifies the location of a file in that computer.
The Uniform Resource Locator was created in 1994 by Tim Berners-Lee and the URI working group of the Internet Engineering Task Force (IETF) as an outcome of collaboration started at the IETF Living Documents “Birds of a Feather” session in 1992. The format combines the pre-existing system of domain names with file path syntax, where forward slashes are used to separate folder and file names. Conventions already existed where server names could be prepended to complete file paths, preceded by a double slash (//).
Every URL consists of some of the following: the scheme name, commonly called protocol, followed by a colon, two slashes, then, depending on scheme, a server name such as exp. FTP. www. etc.) followed by a dot (.) then a domain name (alternatively, IP address), a port number, the path of the resource to be fetched or the program to be run, then, for programs such as Common Gateway Interface (CGI) scripts, a query string, and an optional fragment identifier.
The scheme name defines the namespace, purpose, and the syntax of the remaining part of the URL. The software will try to process a URL according to its scheme and context. The domain name portion of a URL is not case sensitive since DNS ignores case. URLs with https as a scheme require that requests and responses will be made over a secure connection to the website. Some schemes require authentication allow a username, and perhaps a password too, to be embedded in the URL. The domain name or IP address gives the destination location for the URL. The port number is optional; if omitted, the default for the scheme is used. If the port number is omitted for an HTTP: URL, the browser will connect on port 80, the default HTTP port.
Some of the companies provide these URLs for free. A URL is a URI that, “in addition to identifying a resource, provides a means of locating the resource by describing its primary access mechanism (e.g., its network location)