In this article, we will look at two software tools available on the Internet.

Search Engines


Search Engines are programs that search the web. Web is a big graph with the pages being the nodes and hyperlinks being the arcs. Search engines collect all the hyperlinks on each page they read, remove all the ones that have already been processed and save the rest. The Web is then searched breadth-first, i.e. each link on page is followed and all the hyperlinks on all the pages pointed to are collected but they are not traced in the order obtained.

Automated search is the service that is provided by Search engines. An automated search service allows an individual to find information that resides on remote computers. Automated search systems use computer programs to find web pages that contain information related to a given topic. It allows to locate:
 

  • Web pages associated with a particular company or individual
  • Web pages that contain information about a particular product.
  • Web pages that contain information about a particular topic.

The results of an automated search can be used immediately or stored in a file on disk to use it later. The results of a search are returned in the form of a web page that has a link to each of the items that was found. Automated search is helpful when a user wants to explore a new topic. The automated search produces a list of candidate pages that may contain information. The user reviews each page in the list to see whether the contents are related to topic or not. If so, the user records the location or if not user moves on to the page in the list. Search mechanisms uses a similar method of search as in the telephone book i.e. before any user invoke the search mechanism a computer program contacts computers on the Internet, gathers a list of available information, sorts the list and then stores the result on a local disk on the computer that runs a search server. When a user invokes a search, the user client program that contacts the server. The client sends a request that contains the name the user entered. When the request arrives at the server, it consults the list of file names on its local disk and provides the result.


Web Browser


A Web browser is software program that allows you to easily display Web pages and navigate the Web. The first graphical browser, Mosaic, was developed in Illinois at the National Center for Supercomputing Applications (NCSA). Each browser displays Web-formatted documents a little differently. As with all commercial software, every program has its own special features.

The two basic categories of Web browser are:


  • Text-only browsers: A text-only browser such as Lynx allows you to view Web pages without showing art or page structure. Essentially, you look at ASCII text on a screen. The advantage of a text-only browser is that it displays Web pages very fast. There's no waiting for multimedia downloads.
  • Graphical browsers: To enjoy the multimedia aspect of the Web, you must use a graphical browser such as Netscape Navigator or NCSA Mosaic. Graphical browsers can show pictures, play sounds, and even run video clips. The drawback is that multimedia files, particularly graphics, often take a long time to download. Graphical browsers tend to be significantly slower than their text-only counterparts. And this waiting time can be stretched even further with slow connections or heavy online traffic. 

Many different browsers are available for exploring the Internet. The two most popular browsers are Netscape Navigator and Microsoft Internet Explorer. Both of these are graphical browsers, which mean that they can display graphics as well as text.

SUMMARY


I hope now you have an idea in the basic concepts about an Internet. Internet is a network of networks where lot of information is available and is meant to be utilized by you. No one owns the Internet. It consists of a large number of interconnected autonomous networks that connect millions of computers across the world. The unit describes the various tools available on the Internet and the various services provided by the Internet to users. In this unit we have talked about the Electronic mail Usenet and newsgroups, FTP, Telnet and search engines. We also describe the use of frequently asked questions. The unit also describes the importance of Internet addresses. Addresses are essential for virtually everything we do on the Internet. There are many services available on the Internet for document retrieval. For browsing the Internet there are many browsers available such as Gopher and World Wide Web. Both of these browsers are easy to use and most popular browsing mechanisms on the Internet.