TexPREP Summer Camp Computer Science The Internet TexPREP Summer Camp Computer Science

The Internet Internet: is a global network of networks. On top of it we can get different types of services such as: WWW, e-mail, FTP, VoIP, Chat, online games, etc. One of its main advantages is that we can connect networks of different types. Another is that it spans over the whole world.

The Internet bc.theambitious.com

History It became operative in 1969 as ARPANET and after some changes it was named the Internet. It was developed for military purposes but today it is a public, cooperative, and independent network. Although it is not controlled by anybody in particular there are organizations, like World Wide Web Consortium (W3C), that set standards so it can continue growing in an organized way.

How it works Every computer has a unique id (IP address) that identifies it. Information is broken into small packets that are sent through any available path between the sending device and the receiving device following the TCP/IP protocols. Once the packets arrive at the receiver, they are put together in order to form the original message.

Access We typically access the Internet through an ISP (Internet Service Provider). They provide us different ways to access the Internet, some of them are: Dial-up (56 Kbps) DSL (3 Mbps – 24 Mbps) Cable (20 – 60 Mbps, 1 Gbps) Cellular phone (4G LTE: 30 Mbps) Satellite (20 Mbps) Modem Internet

Services The Internet allows us to have access to different types of services: WWW, email, FTP, etc. Most of them are based on the Client/Server model. This means we need to access the corresponding server in order to get the service. For example, to see a web page we need to access a web server; to send an email we need to access an email server; and so on.

WWW WWW stands for World Wide Web. It is a collection of web sites located around the world. A web site is a collection of web pages. A web page is a multimedia document (text, graphics, video, sound, hyperlinks, etc.) To access a web page we need to use a web browser. Each web page has unique id called URL (Uniform Resource Locator). They can be accessed by specifying a domain name or its corresponding IP address.

WWW (continued) It is possible to extend the capabilities of a web browser by installing plug-ins on our computer. With them we can: Play videos or music (Windows Media Player, RealPlayer, QuickTime, etc,) View pdf files (Adobe Acrobat Reader) View animations (Flash Player)

e-mail This service allows us to send and receive messages. We can include attachments in our messages. POP (Post Office Protocol) Incoming servers IMAP (Internet Message Access Protocol) Web based Outgoing server: SMTP (Simple Mail Transfer Protocol)

Netiquette Set of rules that suggest acceptable behaviors users should follow while on the Internet. A few examples: Provide a meaningful subject Explain attachments Use uppercase and lowercase letters Be careful what you send Be polite Use the Bcc function for group mailings Don’t send replies to all recipients

Malware Short for malicious software. These are programs that can affect your computer system in different ways (destroy information, spy, make your computer vulnerable, control your computer, etc.). It includes viruses, worms, trojan horses, and spyware. You should install utilities on your computer that can seek and destroy the malicious programs they find on your computer or prevent them from infecting your system. Examples of these utilities are anti-virus, anti-spyware, anti-trojan, and firewall software.