Copyright Goodheart-Willcox Co., Inc. Chapter 13 Internet and the World Wide Web 515 messages. The fi le transfer protocol (FTP) provides transmittal of fi les between hosts on a TCP network. Upload and Download The basic function of the Internet is to move digital fi les from one computer to another. These fi les can be text, video, image, or audio fi les offi ce documents or any other type of digital fi le. There are two functions to transmitting fi les: • Upload is a user at one computer sending a document to a server. • Download is a user retrieving a document from the server to the computer. The speeds of early Internet transmissions were too low to make the uploading and downloading of anything other than text fi les effi cient. E-mail and basic text-only documents were transferred between computers. These transmissions each represented only a few kilobytes of data. As transmission speeds increased, larger fi les could be effi ciently uploaded and downloaded. Now it is common to send streaming video from one machine to another, which represents the transmission of gigabytes of data. In general, it is considered more important to provide faster download speeds than upload speeds because a user is waiting for the document. Upload on the other hand, could be handled in a slower fashion because it is simply storing the documents and no person is actually waiting for it. Because of limited resources, Internet servers ration transmission times and routinely assign faster speeds to the download function. However, this balance between upload and download has changed with the advent of Internet-based services such as video conferencing. In these applications, it is important to provide real-time interaction. The transmission speed for both upload and download must be as fast as possible for these real-time applications. World Wide Web The World Wide Web (WWW) is a subset of the Internet that consists of a collection of documents connected by universal resource locator (URL) codes and hypertext protocol. Invented by Sir Timothy Berners-Lee in the early 1990s, the web made it easy for people who were not experts in computers to access documents stored on the Internet. Today, there are client programs that provide functionality supported by the above Internet protocols. Servers connected to the Internet have a WWW folder at the root of the computer. Within this folder and its subfolders are all of the accessible documents for the web for the server. Figure 13-4 illustrates how the web works. These are the basic steps: 1. The user either enters a location in the navigation bar of a web browser or clicks a link on a web page, which issues the URL for a document to the browser. Living Online 1.2.10 Living Online 1.1.3.11 Living Online 1.1.1, 1.1.2, 1.1.3 GS4 GS4 GS5