Describe how to access the Internet. What are the providers?

Define browsers and discuss URLs, HTML, javascript, AJAX, applets, and mobile browsers.

 

Answer：

一、Access

Common way to access the Internet is through a commercial Internet Service Provider(ISP).

You can connect to the Internet through a computer. Once connected, your computer becomes an extension of what seems like one giant computer. Use a browser program to access web resources.

• Provide a connection for individuals to access the Internet.


• Use telephone lines,cable, and/or wireless connections

二、Providers

• Using a provider or host computer is the most common way to access the Internet.The providers are already connected to the Internet and provide a path or connection for individuals to access the Internet.

1. a) National service providers
   Example is America On Line (AOL) Access the Internet from almost anywhere in the United States without incurring long distance charges
   b) Regional service providers
   Also use telephones, but you’ll incur long distance charges if you leave the region
   c) Wireless service providers
   Don’t use standard telephone connections. Do use wireless modems and/or other wireless devices

三、Browsers

• Browsers are programs that provide access to Web resources. Browser software lets you:


• Connect to remote computers


• Open and transfer files


• Display text and images


• Provides in one tool an uncomplicated interface to the Internet and Web documents.


• Allow you to surf the Web, easily moving from one site to another Uniform Resource Locators URL


• URL: For browsers to connect to resources, the location or address of the resources called Uniform Resource Locator.URLhas two basic parts:

1. Protocol: used to connect to the resource.


2. Domain name: is the name of the server where the resource is located.

• Hypertext Markup Language (HTML): Once the browser has connected to the web site, a document file is sent back to your computer. This document typically contains html commands.T He browser interprets the html commands and displays the document as a web page.


• Web pages contain links to programs called applets. These are special programs written in a programming language called java and these program can be quickly downloaded and run by most browsers.applet is a small Internet-based program.applets are usually embedded in an HTML page on a Web site and can be executed from within a browser.


• Interactive features on Web pages may be triggered by serial programming instructions written in some languages such as javascript, Ajax, and JAVA. javascript is a lightweight, interpreted programming language. It is designed for creating network-centrist applications. It is complimentary to and integrated with Java. javascript is very easy to implement because it is integrated with HTML. It is open and cross-platform.


• Asynchronous javascript and xml (Ajax)is a term for the process of transferring data between a client script and the server.


• A mobile browser is a web browser designed for use on a mobile device such as a mobile phone or PDA. Mobile browsers are optimized so as to display Web content most effectively for small screens on portable devices.