虽然所有这些服务可以很好地满足用户对信息交换的需要，但用户仍旧还需要具有一些特定的先决条件。用户不仅要知道信息资源所处的位置，而且要知道一些有关的操作命令。为了减轻用户寻找信息的负担，近来出现了一些方便的搜索工具，如Gopher，WWW和Netscape。
World wide web （WWW）is a networked hypertext protocol and user interface.It provides access to multiple services and documents like Gopher does but is more ambitious in its method.A jump to other Internet service can be triggered by a mouse click on a “hotlinked”word，image，or icon on the Web page.
全球网（WWW）是一种网络的超文本协议和用户界面。像Gopher一样，它提供多种服务和文件接入方法，但其方法更加有前途。向Internet其他服务的跳转可在“网”页上由鼠标器点击“热链接”的字、图像或按钮来启动。
As more and more systems join the Internet，and as more and more forms of information can be converted to digital form，the amount of stuff available to Internet users continues to grow.At some points very soon after the nationwide （and later worldwide）Internet started to grow，people began to treat the Net as a community，with its own tradition and customs. 随着越来越多的系统加入Internet，同时随着越来越多的信息可以转变成数字形式，Internet用户所能得到的东西也在继续增加。随着国家（后来是国际）Internet的发展，很快在某些方面人们开始将互联网看作是一个社区，有自己的传统和习惯。For example，somebody would ask a question in a conference，and a complete stranger would send back an answer：after the same question were repeated several time by people who hadn’t seen the original answers，somebody else gathered list of “frequently asked questions”and placed it where newcomers could find it.
例如某些人会在会议上提出一个问题，一个完全陌生的人会传送一个答案；由于一些人没有看到最初的答案而多次重复这一问题，这时另外一些人会搜集一系列“经常提到的问题”并将其放置在新来者能找到的地方。
So we can say that the Internet is your PC’s window to the rest of the world.
所以我们可以说，Internet是你的PC机通向世界其他地方的窗口。
What Can Internet Do for Us？因特网能为我们做什么？
Internet has four main applications as follows：
因特网有如下四个主要的应用：
1．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.
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．News．Newsgroups are specialized forums in which users with a common interest can exchange messages．Thousands of newsgroups exist on Internet，on technical and nontechnical topics，including computers，science，recreation，and politics．
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．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．
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账号的其他计算机上。
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．
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。
The Network Computer
网络计算机
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．
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接到因特网和网络资源上。从这种台式装置上，他们就能分享到任何资源，完成所有目前需要在PC机上进行的计算任务。
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．
网络计算机提供了简洁性，去掉了使PC应用复杂化的软硬件，只留下网络访问与显示功能，实际上，网络计算机在软件、服务、处理、数据和资源上全部都依赖网络。这就消除了周而复始的台式软硬件升级，而是把这个负担放到了网络上。
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．
需要最新的字处理软件或电子表格软件？将它从服务器上下载来运行即可。需要把你做的工作保存起来吗？只需把它送上网络，在那它被安全地存储并作好备份。
Firewall：A Measure of Network Security
防火墙：一项网络安全措施
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．
随着因特网的普及，网络的安全性越来越难以保证，网络遭破坏的事件时有发生。这既有“黑客”们的“光顾”，也有合法授权用户的“特别关照”。而防火墙就是保证网络安全的一种有效措施。它可以保证所有的通信符合安全政策。
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．
曾有两位年轻人非法侵入了大学网络，创建了一个公告牌，并在上面装入了流行的商业软件，还邀请因特网上的用户下载这些软件包。幸好有了防火墙，网络管理员发现系统遭到了破坏。他们检查了审计记录，找到了这两名学生的IP地址、姓名及地点。警察就逮捕了这两名“黑客”。
电子函件
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．
因特网的一个重要应用是计算机用户间利用电子函件相互通信。电子函件使用户可以用电子手段传递和接收消息、文本和数据。电子函件的功能非常类似于邮箱：无论接收者是否在网络上，用户都可以向他发送消息，该消息被保存起来，同时向接收者发送一个信号表明有一个消息在等待处理。
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．
电子函件传送消息已经代替了电话。用户可以在方便的时候再去对它作出反应，而不会被打扰，并可以在屏幕上显示消息或把它打印出来。
Electronic Bulletin Boards
电子公告板