Unit 2
网上冲浪net-surfing 下载downloading 电子邮件E-mail 电子商务E-business 信息时代information age 网站website 信息高速路information expressway 网络 network
the World Wide Web万维网(WWW) log on to the net登录上网
web browser网络浏览器 pull-down menu下拉菜单 search engine搜索引擎 dial-up connection拨号上网 main page主页 CD=compact disk光盘
Internet has four main applications as follows：
l．E－mail． With Internet， people can compose， send， and receive electronic mails． Many people get dozens of messages a day and consider it as their primary way of interacting with the outside world, far outdistancing the telephone and snail mail.
2．News． Newsgroups are specialzied forums in which users with a common interest can exchagne messages．Thousands of newsgroups exist on Internet，on technical and nontechnical topics，including computers，science，recreation，and politics．
3．Remote login．Using the Telnet，Rlogin, or other programs， the user anywhere on Internet can log into any other machine on which he has an account．
4． File transfer．Using the FTP program， it is possible to copy files from one machine on Internet to another． Vast numbers of articles， databases， and other information are available in this way． The Network Computer
The network computer， also known as the Internet toaster，Internet appliance or Internet device，is the low cost，no maintenance desktop device． It allows users to effortlessly connect to Internet and network resources． From there， they can share any resource and perform all computing tasks that they currently do on their PCs．
The network computer offers simplicity．Stripped of the hardware and software that complicate the PC life and only capable of network access and display, the network computer relies on the network for virtually all software， services， processing， data， and resources． It eliminates the continuous cycle of desktop hardware and software upgrades， pushing that burden instead on to the network． Need the latest word processor or spreadsheet？ Run it off the server， Want to save your work？ Just send it off to the network，where it will be stored secured, and backed up． Firewall： a Measure of Network Security
With the popularity of Internet，it is increasingly difficult to guarantee the network security．Sometimes the network was breached because of not only hackers’ visit but also authorized users’ care out of ordinary. Firewall just is an effective measure of network security．It will ensure that all communications conform to your Security policy．
Once two lads broke into the university network，created a bulletin board，loaded popular commercial software on it and invited users across Internet to download the packages．Thanks to a firewall, network administrators found the system breached. They checked the audit and found the students’ IP addresses， names and location． The police arrested the two hackers． E－mail
One important application for Internet is communication between computer users by the electronic mail，or E－mail． E－mail allows users to electronically transmit and receive messages，text， or data．E-mail functions further like a mailbox：the user can send messages whether or not the intended receiver is currently on the network and the message is stored， along with a signal for the receiver that indicates that there is a message waiting．
E-mail has replaced the telephone for many messages．Users can respond when it is convenient，without being interrupted, and can get their message either on-screen or in the printed form．
Electronic Bulletin Boards
Another interesting application for Internet is the electronic bulletin board which is also called bulletin board service, BBS for short. It allows users to post and retrieve messages that are not directed to a specific user,
much like announcements are posted on an office bulletin board. BBS has been used for everything from dating service and want ads to highly specialized applications such as the exchange of research data in a narrow scientific field.
因特网能为我们做什么？
因特网有如下四个主要的应用：
1．电子函件。在因特网上，人们可以创作、发送和接收电子函件。许多人每天收到成打的电子函件信息，这大大超过电话和蜗牛式的普通邮件，他们把它看作与外界交流的主要方式。
2．新闻。新闻组是供具有共同爱好的用户交流信息的限定范围的论坛。在因特网上，有上千个技术性和非技术性的新闻组，涉及计算机、科学、娱乐和政治等专题。
3.远程登录。在因特同任何地方的用户都可以使用Telnet、Rlogin或其他的程序登录到他具有帐号的其他计算机上。 4．文件传输。在因特网上，使用FTP程序可以从一台计算机向另一台计算机拷贝文件。大量的文章、数据库及其他信息都可以通过这种方式传输。 网络计算机
网络计算机，也叫“因特网烤炉”、因特网装置、因特网设备，是一种价格低廉、无需维护的台式装置。它可以让用户不费力气就能
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