URL stands for Uniform Resource Locator. It is the unique identifier for a specific resource and it identifies it location based on the format and string in the URL. A typical example can be seen when we access a website over the internet. The website address that we are going to enter is just like “http://www.benefitsandadvantages.com”. This here is the URL for a specific resource called abc.html. The URL specifies it location as a belonging to a specific domain which will be resolved by the DNS into the IP address of server. The protocol here is specified by the http.
The URL is different from the the URI which is just the indicator for a resource. The URL contains the protocol information that is placed in front of the URL followed by a “://”. This part is followed by the domain name which identifies the server where it belongs to. This can be the Domain name or the direct IP. For example the access to the FTP server resources are directly given as FTP://192.168.1.200/file.exe etc. Here the direct IP is accessed and there can also be a specific port that is to be used for the transfer. In such a case apart from the protocol and domain there is also an extension to domain name with a :[portnumber]. This is the primary access information.
Different resource types:
The URL accesses can lead to any resource type. A trivial case is where a direct file is starting to be downloaded to the client when accessed. There can be PHP pages, streaming data access etc. In different cases and depending on the different protocols the client and server actions might be different.
Global Access:
The URL when associated with the website is globally accessed through the various DNS servers. These are the once that resolve the domain to the specific IP address. Domain registration and hosting have to be correlated properly to have this working for every website. A static IP address has to be assigned for the servers so that global access always available.
Relative URL:
When internally accessing a resource, like a webpage on a server is referring to another page on the same server, the URLs need not be specifying the entire Global URL of resource, instead can just start referring to the resource from its folder. This type of URLs are referred to as Relative URLs. On the other hand the location referred from the root path (the base folder of the Linux file system or from the Drive Letter in windows system) is referred to as Absolute URL.
URLs and their access give the corresponding result to the client side, whether it is successful or not and there are usually different error codes for various types of error that can occur during the access of the resource. The URLs are just the starting point for initiating the data transfer and any protocol that is followed comes into play after the resource location is done using the URL.