Before the Web was developed, images would primarily be downloaded manually from file servers or from binary newsgroups on Usenet, and displayed with a separate image viewer. The expansion of the Web in the 1990s brought text and images together, allowing for inline display of images without separate downloading, but still required the above expertise and methods to make the images available.
Domain names are often seen in analogy to real estate in that domain names are foundations on which a website can be built, and the highest quality domain names, like sought-after real estate, tend to carry significant value, usually due to their online brand-building potential, use in advertising, search engine optimization, and many other criteria. 

One of the primary new features of the early and developing Web that enabled the easy sharing of images and other data, was the concept of being able to upload or HTTP POST a file via the web browser to the remote server. This alone helped to eliminate all the complex steps of needing to understand command line tools like FTP or uploading via a modem terminal.
Sorry Jezelll, had to throw a downvote. This is not what I would consider 'plain english' :( I don't have a problem with the intent of your definition, but using words like 'operation', 'remote server', 'invoked' and 'specification' makes it hard for beginners to understand. See Mitchel Sellers answer as an example of 'plain english'. – Dhaust Jun 30 '09 at 23:53
By definition, a domain name is simply a human readable form of an IP address. In function it is the destination that you type into a web browser in order to visit a website, such a Metaphorically, it is very similar to how you would scroll to a contact in your cell phone rather than manually dialing the person by entering their full phone number; the phone number would be an IP address and the saved contact would be a domain name. Always buy a domain with a reputable domain registrar.

To display website content and access email, a domain name must connect to a web hosting account, a Cloud Server, or a Dedicated Server. Web Hosting Canada makes it easy for you to reserve your domain name while ordering a web hosting account. We include a free domain name registration with certain hosting packages. You can also associate multiple domain names with the same website, or multiple domains to separate websites on the same hosting account at no extra cost.
Image hosts also allow tools such as the ability to create photoblogs/galleries with your images, or add them to a slide show for easier viewing. Some offer more advanced tools such as the ability for anl to ato an image they uploaded, sideloaders, or browser sidebars. Other hosts have introduced novel features such as the ability to automatically resize images down to a user-selected size. A Flickr tool allows one to upload photos using a camera phone with email capability.[1]
Intercapping is often used to emphasize the meaning of a domain name, because DNS names are not case-sensitive. Some names may be misinterpreted in certain uses of capitalization. For example: Who Represents, a database of artists and agents, chose[23], which can be misread. In such situations, the proper meaning may be clarified by placement of hyphens when registering a domain name. For instance, Experts Exchange, a programmers' discussion site, used, but changed its domain name to[24]