1. COM: 111 Introduction to Computer Applications Department of Information & Communication Technology Panayiotis Christodoulou

2. Networks A network is a group of two or more computer systems linked together. There are many types of computer networks, including: 1.local-area networks (LANs) : The computers are geographically close together (that is, in the same building) 2.wide-area networks (WANs) : The computers are farther apart and are connected by telephone lines or radio waves. Panayiotis Christodoulou

3. 3.campus-area networks (CANs): The computers are within a limited geographic area, such as a campus or military base. 4.home-area networks (HANs): A network contained within a user's home that connects a person's digital devices. Panayiotis Christodoulou

4. Servers Servers operate within a client-server architecture. Servers are computer programs running to serve the requests of other programs, the clients. Thus, the server performs some tasks on behalf of clients. The clients typically connect to the server through the network but may run on the same computer. Panayiotis Christodoulou

5. Data Communications Hardware Data communications, or telecommunications, is the electronic collection and distribution of information between two points. Data communications hardware is used to transmit digital information between terminals and computers, or between computers and other computers. Panayiotis Christodoulou

6. Communication Channel Is the medium through which digital information must pass to get from one location to another. Information sent through a communications channel has a source from which the information originates, and a destination to which the information is delivered. Panayiotis Christodoulou

7. Data can be transmitted between 2 points in 2 ways: 1) Serial Transmission data is sent bit by bit Panayiotis Christodoulou

8. 2) Parallel Transmission all bits are sent at once, and each bit is sent on a separate wire Panayiotis Christodoulou

9. Modem A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog waves. A modem converts between these two forms. Panayiotis Christodoulou

10. Router Networks use a variety of communications protocols and operating systems. Therefore, incompatible networks cannot directly “talk” to each other Routers are the primary hardware/software technology used to connect incompatible networks. They carry out the necessary protocol conversions. Panayiotis Christodoulou

11. Internet The Internet is a global network connecting millions of computers. The Internet is used to send information quickly between computers around the world. Created by the United States Department of Defense Advanced Research Projects Agency and connected in 1969 Internet Service Provider (ISP), refers to a company that provides Internet services, including personal and business access to the Internet Panayiotis Christodoulou

12. World Wide Web The World Wide Web ("WWW" or "The Web") is the part of the Internet that contains websites and webpages. It was invented in 1989 by Tim Berners-Lee at CERN, Geneva, Switzerland. Sir Tim Berners-Lee created a new language called HTML. Websites are composed of pages linked by hypertext links. They are all written in HTML. In order to see the World Wide Web one needs a computer and a computer program called a web browser. One also needs a connection to the Internet Panayiotis Christodoulou

13. Email An email address identifies an email box to which email messages are delivered. panchristodoulou @ hotmail.com usernamedomain address mail-server Panayiotis Christodoulou

14. Which activities increase the amount of transferred data? Sharing files via peer-to-peer software Streaming visual files, as when communicating via Webcam (Skype, MSN) Videoconferences Watching online video sites like YouTube Downloading movies and music Listening to Internet radio (audio streaming) Playing network games (game console or computer) Panayiotis Christodoulou