What is the Internet? A world-wide computer network made up of tens of thousands of smaller networks. It’s the biggest network of all! So, what is a network?

Computer Networks A network is a collection of computers and other devices that communicate to share data, hardware and software. A server coordinates the sharing.

Network Servers A server is a computer running special software that allows it to process requests from other computers that it is connected to.

Physical Connections Computers communicate with the server through cables, phone lines, wireless broadcast or satellite. A server may store and forward: web pages filesmedia

Who runs the Internet? No one “owns” the Internet. The computers on it are owned and operated by individuals, organizations, and major communications companies like AT&T and Verizon. The Internet is decentralized – there is no main computer that all packets must go through.

How do you get access?  Businesses, organizations and home users contract with an Internet Service Provider (ISP).  An ISP maintains communications equipment to connect you to the worldwide network.

Sign up with an ISP Your account with a service provider usually gives you:  Access to the Internet  addresses  Storage for a web page  Security features

Connecting to the Internet Since the Internet is a world-wide network of smaller networks, your computer join the network. There are several different ways…

Be On a LAN Connected to the Internet  The LAHC computer labs are connected in a local area network (LAN) that gives access.  The LAN is connected to the Internet through a router.  LAHC pays to connect to high-speed Internet through a special phone line.

Methods for Connecting At home you need to make a connection to the Internet network through: Phone lines Cable TV Wireless Satellite (used in remote areas, expensive)

The Phone Lines Phone companies provide connection options for homes and businesses. From slowest and cheapest on up they are: Dial-up DSL Fiber-optic (FIOS by Verizon)

Dial-up  Phone lines are analog (for sound waves). Computers are digital. A modem is used to convert the signals back and forth.  A cable runs from the back of the computer to the wall jack. You can’t talk on the phone while connected to the Internet.  Modem speeds are 56Kbps (thousands of bits per second)

DSL  Runs over existing phone lines.  You must be within 3 miles of a telephone switch for it to work well.  DSL costs more than dial-up, but is much faster, up to 1.5 Mbps (M=millions).

Cable Internet  Speed varies.  There are 500 households per neighborhood connection point for Cox. 2 or 3 big downloaders can slow response time for everyone.  Can be over 1.5Mbps.

Cable TV and DSL  Cable and DSL Internet require a network board installed in the PC.  A cable runs from this to an external modem box or router.  Connection is always-on, when your computer is on you are on the Internet.  Called broadband because of high data capacity

Wireless (Wi-Fi)  A WISP maintains a public wireless network.  A hotspot is a location where a PC equipped with a wireless card can connect to the network.  Available in airports, hotels, restaurants, college campuses, new buildings at LAHC, the cafeteria, Library and Seahawk Center.  Disadvantages: slow, not secure, susceptible to interference

What is the Web?  The World Wide Web is a collection of linked web pages  A Web page is specially coded document that can contain text, graphics, videos, and sounds  A Web site consists of one or more Web pages located on a Web server

Browser Software  Browser software runs on your PC and requests and displays web pages  Examples are:  Internet Explorer (IE)  Firefox  Netscape Navigator  AOL

URL A URL is the address of a web page. You enter a URL in the browser or click a link to a page and the browser software requests the page from the web server.

HTML  Web pages are stored in HTML format (.htm ending). HTML is a set of instructions that the browser interprets to display the page.  For example, Internet Backbone would cause the words Internet Backbone to display underlined as shown.

How do I use a URL to go to a Web site?  To enter a URL:  Click Address box on browser window  Type URL  Press Enter key  Browser formats and displays page on screen  Be very precise when entering URL  Don’t use any spaces  Exactly duplicate uppercase and lowercase letters  Complete URL usually starts with  Don’t have to type this, browser fills in

How do I use links on a Web page?  A hypertext link is a connection between two Web pages  Contains URL of Web page, so it can be used to “jump” from one Web page to another  Links usually displayed on Web page as underlined text or as graphic  When positioned over a link, arrow-shaped pointer turns into  When you click link, Web page displayed

How do I print a Web page?  Click Print button in toolbar or select File, Print from the menu bar  Some Web pages include a link to a “print friendly” version of page  Designed to use color in way that single page won’t use all your printer ink  Look for “printer friendly” link before you start printout  Use Print Preview to make sure you’re not printing a huge number of pages.

What should I do when I get an error message?  If a Web page can’t be loaded, the browser displays an error message  If the URL was correct the page has moved, was renamed, or deleted  Occasionally a message appears if the site is too busy to respond – try later End of Lecture