Wondering What is a URL is a Common Thing
A URL at its most basic is a website address, but first you have to understand something about computers.
Computers identify themselves as numbers when on a network. They use their network address as who they are.
For example, an internet protocol address, or an IP address, at least in the most common version four format, consists of 4 (3 digit maximum) numbers, or octets, separated by periods. (xxx.xxx.xxx.xxx) These periods are also called “dots” when being referred to verbally. There are Class A, B, & C IP addresses out there, and then there are the non-routable segments that exist behind firewalls and routers.
If this is too much for you, you can skip the real technical stuff, but try to stick with me for the big picture so it all makes sense. (hopefully)
An internet connected server exists at an IP address. So, the webserver for some site, let’s call it “CNN.com”, and that actually exists as an IP address, which is 18.104.22.168.
You would be hard pressed to remember that, so the domain name system (DNS) and the webserver ID of WWW maps to a name, say cnn.com or www.cnn.com. That’s much easier to remember for you and me.
So, What is a URL Then?
A URL is a Uniform Resource Locator, which means that there is a uniform way to call up a website by it’s name, but there are specific parts to it.
The protocol that is being utilized is the first part. Web browsers can speak different protocols. For example, if you wanted to talk to an FTP site (which means File Transfer Protocol), then it would start with ftp://. Many people don’t use FTP anymore, but some do, and most times you use a specialized FTP client software for that, but web browsers can also do FTP via specifying the protocol this way. I only add that in there to let you know that there is a difference between protocols and that your web browser can actually utilized several, even if the main one is http, the protocol of the World Wide Web. A long time ago there was also Gopher, which would be “gopher://”, but we won’t get into that one here.
If you want to call a website, you need to speak Hypertext Transfer Protocol (http), so the most common URL’s out there are in the http format. They start with http://.
Then there is the parent and subdomain. The parent domain is the cnn.com in the www.cnn.com. CNN.com can host ftp servers, WWW servers, other servers with other names… These can show as subdomains. It can get confusing because a subdomain doesn’t have to mean another computer. I can setup a subdomain under an online account and name it for a function that I need and it will come before the parent domain. Say I have a blog at my domain and I want to just use a subdomain for it. I can call it “blog” and then the subdomain with the parent domain would be blog.somedomain.com.
What I am trying to get through here is that “www” is usually used for, but not always” for, web servers.
So, http://www.cnn.com is the URL, or Uniform Resource Locator, for CNN’s main web server/site.
What is a URL can be Even More Complicated
There are specialized URL’s of all sorts.
A static URL is the kind I showed above. It just defines a machine or web service.
There can be parameters that are part of a URL that tell a web service a way to act on it in order to serve a custom page or give credit for something like if you are sending traffic to a site and you need to get credit for that.
These URL’s usually have a question mark and/or equal signs with codes in them. This enables an active dynamic site to send custom content to a requester (you).
Take this one, for example: (this is a real URL so I put it in quotes so my blog wouldn’t replace it with the actual video)
Here we have the secure sockets encrypted version of the HTTP protocol, which adds an “S” for “secure sockets layer”. It encrypts the data being shared between the site and the viewer.
Then you get the “www” and site domain, followed by the dynamic part of the URL which tells the site which video to serve to the user. That is the watch?v= part. That basically stands for watch video code number “blah blah blah”. You can see the long code. YouTube has so many videos catalogued that they need long codes like this to keep them all unique.
One more part of a URL that MAY be present is the port number. Different services operate on different ports that the computer listens on. The port for http is the default port 80. Whenever you type a URL into your browser, it assumes port 80 and you do not have to specify it in the IRL (although you can). Some URL’s require a specific port to be specified to get to whatever you need, so in that case, you add the port number, like this:
Another thing is that the default file that the web browser looks for in any path is index html or index.htm – which is a hypertext document. IF you needed a document names something else, it would need to be specified beyond the folder name, like this:
And, in the case of a dynamic retrieved document, like from a database, it may be a folder name that maps to an id in the background, so you specify just the URL which is in the familiar folder format but the web server would know that that maps to a specific file that is ID’d to that location.
Most people will just need a website address or click on a link in a search engine like Google and will be directed where they need to go.
A system that requires users to know so little about how it actually works and remains as effective as the World Wide Web is for the general non techie public is a good one, and a testament to the user friendliness of this amazing Internet platform.
What is a URL is Summarized Here
There may be several ways to explain what is a URL, but that is the best way that I could figure out how to relay that information.
In short, what is a URL is nothing more than a human readable pathway to a website, web page, or web item, which tells the Internet which site, page, or item to send to you.
It replaces the computer readable binary numbers which at its core are 4 octet binary numbers and translates them to a human readable and easily remembered format, which utilizes the Domain Name System (DNS) to translate the IP addresses (xxx.xxx.xxx.xxx) to domain names, and then, as I explained, it adds in the hypertext protocol (http) parts and any dynamic parts that identify specific world wide web items that you may be looking for.
I hope that this answered you question about what is a URL.
For more great stuff, check out the rest of my blog.