1. Date of download: 5/28/2016 From: Medical Resources on the Internet Ann Intern Med. 1995;123(2):123-131. doi:10.7326/0003-4819-123-2-199507150-00008 Components of a Uniform Resource Locator (URL).World Wide Web browsers use this format to locate documents. The leftmost set of characters identifies the mode of access. For the World Wide Web, the access method is the hypertext transport protocol (http). Other common access methods are telnet, FTP [file transfer protocol], and gopher. A colon and two forward slashes follow the access method. The next entries are 1) a computer name; 2) the directories that lead to the document, with entries separated by forward slashes; and 3) the name of the document or file. If the directory path and file name are omitted, as in the second example, the main menu or Web page at the site is displayed. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

2. Date of download: 5/28/2016 From: Medical Resources on the Internet Ann Intern Med. 1995;123(2):123-131. doi:10.7326/0003-4819-123-2-199507150-00008 Naming and numbering scheme for Internet computers.A computer at M.D. Anderson Cancer Center in Texas that can be reached by gopher is used as an example. Computer names are strings of characters separated by periods. The leftmost string is called the host name, and succeeding strings identify subnetworks, the network, and the top-level domain to which a computer belongs. A computer name may have several or no subnetwork names. Each computer name has an associated Internet Protocol address consisting of four numbers, each in the range 0 to 255, separated by periods. Depending on the type of network, the leftmost one to three numbers identify the network, and the remaining numbers identify the computer (the host). Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians

3. Date of download: 5/28/2016 From: Medical Resources on the Internet Ann Intern Med. 1995;123(2):123-131. doi:10.7326/0003-4819-123-2-199507150-00008 The principal National Science Foundation network (NSFNET) in the United States.The structure for ANSNET (Advanced Network and Services network), the major high-speed Internet network in the United States through the end of 1994, is shown. Because most of the funding for this network came from the National Science Foundation, the network was usually referred to as NSFNET. The links in the network are fiberoptic cables leased from MCI that can transmit 45 millions bits of information, equivalent to 1000 pages of text, per second. In 1995, NSFNET stopped funding ANSNET. Currently, most of the long-distance Internet service in the United States is provided by telecommunications companies, such as Sprint and MCI. Figure Legend: Copyright © American College of Physicians. All rights reserved.American College of Physicians