What is a web domain?

What is a web domain?
In the simplest sense, a web domain is a unique name given to refer to a particular collection of resources on the internet, such as www.google.com, or joe@google.com (with "google.com" being the domain in both cases).To delve deeper, think of a domain as a unique address, similar to the numbers on a house. There can only be one "123 Acorn Avenue" in zip code 11111, for example. Similarly, a domain name is an address for a specific website or internet resource. When you type www.google.com in your browser's address bar, you can only be taken to one -- and only one -- website.Now to get nitty gritty -- websites are all hosted (that is, stored) on web servers throughout the world. Each machine has an IP address that identifies that particular machine (think house numbers again). When a website is set up, a domain name is reserved and registered into one of the domain name registrar's databases, and is then usable only by that particular registrant for a set period of time. Once the website is ready to be launched, information is updated with the domain registrar (usually by the person who reserved the domain name) to indicate the name of the web server where the site is being hosted (using the server's IP address). Now whenever the URL is typed into an address bar, the domain name service (DNS) will automatically direct the browser to the web server to server up the correct pages.There are also "subdomains", which can be thought of as suite or apartment numbers (if we want to go back to our house address analogy). Subdomains are often used for sections of a site that provide different functionality. For example, you may have a company site with a URL of www.company.com. Perhaps this company also has an online store. They *could* make a subfolder within their site and have people get to their store by going to, say, www.company.com/store, but they could also set up a subdomain, such as http://store.company.com. Some companies will use subdomains to denote different functions within their site, or perhaps different divisions. Subdomains can also point to different server clusters to provide load balancing across a site if it is a very busy or resource intensive site.