1. How the Web Works AGED 3142

2. How the Web Works Most people use an internet service provider (ISP) or an online service provider (OSP) like AOL to access the internet through a modem –(average modem connection=56,000 bps; cable modem= 500,000 bps) The U of A computer labs have their own direct connection to the internet through an internet server –(T1 connection=1,544,000 bps; T3=44,736,000 bps)

3. How the Web Works Modems convert digital information to analog information that can travel over the physical lines that make up the internet These lines include phone lines (twisted pair and optical fiber), coaxial cable, satellite airwaves, then they convert incoming analog signals back to digital Digital conversion takes time and slows download speeds

4. How the Web Works Information downloaded to your lab computer from a Web server in India, for example, probably follows this route: Server in India – Regional network in Asia – backbone network – regional network in U.S. – U of A server – PC in computer lab All the files related to a Web site are stored on a server (usually owned by an ISP/OSP or by a large company or organization) Every server has its own address called a URL (uniform resource locator)

5. How the Web Works URLs contain the following elements –access method (usually hypertext transfer protocol -- http://) –location or domain name (www.uark.edu) –directories and HTML file (/depts/aeedhp/courses/aged3143/index.htm) So, the address for the AGED3142 course home page is http://www.uark.edu/depts/aeedhp/courses/aged3143/index.htm

6. How the Web Works Organizations like InterNIC, working with the World Trade Organization, register domain names for $35 and up Each web site is a collection of pages linked by hypertext that can be read with a web browser, like Netscape Navigator or Microsoft Internet Explorer When you “open” a web site, your computer downloads each individual file associated with each page to its RAM and displays the visual images on your monitor

7. How the Web Works Download time is dependent on a few factors: –Connection speed (modem) –Computer speed (speed of processor and amount of RAM) –Network bandwidth –Size of files –Server speed

8. How the Web Works The files are “cached”, or saved temporarily, in your computer’s memory so when they need to be loaded again they load very quickly If the browser’s cache files are not cleared occasionally, you may not be looking at the most recent version of a page Cached files are a record of where you’ve been recently on the Web

9. How the Web Works This has been a brief overview. The intricacies of how the Web works could fill an entire semester. We haven’t even touched on e-commerce, networked databases, web security, or many other aspects of the Internet and the Web.