1.5: What Web addresses mean
When the Internet was in its infancy, it consisted of a small number of computers hooked together with modems and telephone lines. The only way to connect with another computer was to provide the IP address of that computer. A typical IP address might be 184.108.40.206.
As more and more systems came online, the number system became unwieldy. The problem was compounded by the necessity to extend Internet access to those lacking knowledge of the computer’s inner workings.
The first solution to the problem was a simple text file maintained by the Network Information Center that mapped names to IP addresses. Soon this text file became so large, it was too cumbersome to manage.
In 1983, the University of Wisconsin created the Domain Name System. It maps text names to IP addresses automatically. The user needs to remember only www.stthomas.edu, for example, instead of St. Thomas’ IP address.
When you use the Web or send an e-mail message, you use a domain name to do it. For example, look at the Uniform Resource Locator (URL) in the image above.
- The protocol: “http” means “HyperText Transfer Protocol.” It tells your browser what languages and conventions to use to read the page.
- The top-level domain: .edu Think of the first-level domain as the Web site’s family name.
- The second-level domain: stthomas. Second-level domains commonly refer to the organization that registered the domain name. NOTE: Some domain name registries introduce a second-level hierarchy to the top-level domain that indicates the type of organization. For example, for the .uk top-level domain, a college or other academic institution would register under the .ac.uk ccSLD, while companies would register under .co.uk.
The host or server. It is the name of the storage area where the Web site is located.
- St. Thomas, for example, has many, many Web servers, computers that house its Web pages. The host could be a particular server.
- The servers themselves often are divided into other areas that contain groups of Web pages; these also could be addressed as hosts.
- Some other St. Thomas hosts: www, courseweb, personal, mail. The courseweb server is for instructional material for classes.
The path: mjodonnell/cojo258/chapter01/section1-4.html. The path lists the folders and subfolders where web pages are stored, listed from the parent folders to their child folders until you get to the folder holding the desired web page.
- So on the St. Thomas courseweb server, a folder named mjodonnell is stored.
- Inside of it is a folder named cojo258.
- Inside it is another folder named chapter01.
- Inside that last folder is where you will find this page, section1-4.html.
- The page name, section1-4.html, is included in the URL to take you to that specific page. The page name is not needed for the root page in each folder named index.html or default.html. The browser automatically looks within the directory for those names when no page is included in the URL.