World Wide Web

The World Wide Web (commonly referred to as WWW or the Web) is a service on the Internet. It consists of sets of linked documents known as webpages which can be viewed using a program called a browser. The links on a webpage (called hyperlinks) contain the Web address of the webpage that will be displayed if the user clicks on the link.

The Web address of a webpage is also known as a URL (Uniform Resource Locator) e.g. http://www.hw.ac.uk/libWWW/irn/ irn.html. The URL consists of a number of separate parts divided by forward slashes (/). This example indicates the following:

http://\s known as the protocol prefix and indicates that the hypertext transfer protocol (an agreed communications standard for webpages) should be used to transfer the webpage across the Internet.

www indicates that this is a World Wide Web document i.e. a webpage.

hw.ac.uk is the domain name and indicates the network domain in which the webpage is stored.

ac is the domain name extension andindicates the type of domain e.g. ac or edu is an educational domain, co or com is a company.

uk is the country code indicating that this webpage is stored on a computer in the United Kingdom.

libWWW/irn gives the path of the directory (or folder) where the webpage is stored on the server.

irn.html is the name of the webpage file. The extension used in webpage filenames is either htm or html to indicate that the file is written using HTML (hypertext markup language).

When a user clicks on a hyperlink on a webpage, the browser program contacts a server computer known as a DNS (Domain Name System) server to look up the IP (Internet Protocol) address (the unique 32 -bit binary number) of the remote Web server computer (the computer storing the webpages) given in the URL of the linked webpage. The DNS has a stored table of names and addresses of nodes (a network terminal or point where a computer is connected to a network) on the Internet. The request for the linked webpage is then sent to a computer or electronic device known as a router that uses the Internet address obtained from the DNS server to route the request (decide on the best Internet path to send the request).

The message requesting the webpage is divided up into small sections called packets and each separate data packet is passed from router to router until they all reach the remote Web server where they are put back together again. The remote Web server sends the requested webpage back to the browser computer that made the request in a similar way using the IP address of the browser computer to determine the best available route for each packet. When the packets arrive at the browser computer, they are combined and the requested webpage is displayed in the browser.

Special websites (e.g. AltaVista) provide a facility known as a search engine that can be used to search for other websites. A search engine uses special programs to collect information about websites on the World Wide Web and stores the information in a database (a type of applications program used for storing information so that it can be easily searched and sorted). The user can then search the database to obtain a list of links to relevant websites. To search using a search engine, the user types words (known as keywords) into a text box (called a search box). The search engine then displays a list of website links that are relevant to the given keywords. Keywords can be used to form search phrases by putting quotation marks around the keywords and they can be combined in different ways using special logical operators such as the words OR, AND or NEAR which can be grouped by enclosing them in brackets. Sometimes, symbols such as + or – can be used to represent the operators. Special symbols known as wildcards can also be used with keywords. These symbols represent certain characters or combinations of characters. For example, an asterisk (*) is often used to represent any combination of characters. A search for 'col*' would look for any word beginning with 'col'.

As well as keyword searches, search engines can be used for field searches. This allows the user to search webpage fields such as the title field of a webpage or its Web address. The Web address is sometimes referred to as its URL (uniform resource locator).

The user can store the links to useful websites using a bookmark facility in the browser program used to view the web pages. The webpage that is set to be displayed when the browser program is first started is referred to as the user's homepage. The user can return to the homepage by clicking a button known as the Home button in the toolbar at the top of the browser program.

Because a video signal contains so much data, it is difficult to download it from an Internet server (copy it to a client computer from a server computer), in real-time i.e. so that it can be viewed immediately without any delays or gaps. The connection would need to have a huge bandwidth (signal capacity). One way of doing this with a normal Internet connection involves using a section of memory as a storage buffer (a storage area for temporarily storing data from a fast source so that it can be fed at a steady rate to a slower system). This allows part of the video signal to be downloaded and stored so that the user can begin to view the video before it is completely downloaded. Feeding the video signal from the storage buffer to the display makes space in the storage buffer for more of the video to be downloaded. Therefore, as the user is watching the first part of the video, the next part is being downloaded into the storage buffer. The video can therefore be shown to the user at a steady rate. This method of downloading video signals using a storage buffer to obtain a steady display is known as streaming.

4. Read the text again and answer the questions:

1. What is the World wide Web?

2. What can you do with the help of a browser?

3. What do hyperlinks contain?

4. What is the other name of a Web address of a Webpage?

5. What are the parts of a URL?

5. Give Russian equivalents to the following words and phrases:

World Wide Web, a service on the Internet, hyperlink, user clicks on the link, Web address, forward slash, protocol prefix, hypertext transfer protocol, domain name extension, educational domain, country code, the path of the directory, stored on the server, hypertext markup language, remote Web server, node, router, to route the request, separate data packet, IP address, combine, search engine, database, relevant website, search box, quotation marks around the keywords, in brackets, wildcards, any combination of characters, title field, by clicking a button, toolbar, download from an Internet server, huge bandwidth, without any delay, storage buffer, to obtain a steady display, streaming.

6. Give English equivalents to the following words and phrases:

Всемирная паутина, связанные документы, интернет страница, косая черта, путь, папка, язык гипертекстовой разметки, сетевой терминал, запрос, маршрутизатор, направить запрос, разделен на пакеты данных, определить лучший доступный путь, отображается в браузере, поисковая система, хранить информацию в базе данных, ключевые слова, окно ввода текста, кавычки, звездочка, символ (2), скобки, закладка, домашняя страница, немедленно, без задержки, мощность сигнала, широкая полоса пропускания, буфер хранения, с постоянной скоростью, потоковая передача данных.