# K-12 School Computer Networking/Chapter 27
## Introduction

Along with the development of internet, the Web has revolutionized the availability and access to information. Billions of web pages may be viewed through search engines. People usually open “Google” or “Yahoo” to find what they want. As to students, they are used to rely on search engines to assist their homework. However, although each student appears to know how to use the Internet at present, the reality is that few of them know how to search effectively for academic purposes. They often lost themselves in mass information and finally this lack of training translates into poor school work.
Furthermore, students tend to rely on simple Google searches. They didn’t know: (1) how search engines determine their results and rank the results, (2) which sources are more relevant and credible, and (3) Beyond Google, what other specialize search engines exist for collecting reliable information. This entry will provide a general overview of search engines and introduce some search skills. Technology coordinators, teachers and librarians may conduct an Internet Hunt workshop in which students learn how to use couples of unique search engines to find answers to their questions.

## Search Engine

Some basics about Search Engine are introduced in this part.

#### What’s a Search Engine

A Web Search Engine is a tool designed to search for information on the World Wide Web. The search results are usually presented in a list and are commonly called hits. The information may consist of web pages, images, information and other types of file.
Search engines are free. You don’t need to pay for any search engine. There are 20-30 major search engines, like Google, Yahoo, Windows Live. However, no single search engine can search the entire Web at one time. Using search engine effectively is not an easy thing. It will take time and practice with different search engine to know which one is best for your specific search.

#### How does a Search Engine Work

When a search engine operates, it follows the following order: web crawling, indexing and searching. Hundreds of thousands web pages are retrieved at a frequency by a web crawler or spider – an automated web browser which follows every link it sees. Web crawler places the initial set of URLs in a priority queue and obtain the next URL to download the webpage. After that, it will extract any URLs in the downloaded page and put new URLs in the queue and repeat. However, along with the appearance of robots.txt in some websites - a file that define how the content of each page should be indexed, there are some exceptions. Search engine will conditionally search this site according to the requirements within the robot file.
After the crawling, data about web pages are stored in an index database for the future query requests. Different search engine have various algorithm to rank the web pages in the database. They will consider the popularity, relevance and credibility of the information and always give priority to major sites and to rapidly changing sites. When a user enters a query into a search engine, the engine checks its index database and provides a list of best-matching web pages. The items in the list usually contain a short summary that includes the documents’ title and parts of its content and a URL to this specific website. Most search engine support the use of Boolean Operators (AND, OR and NOT) to further specify the search query. Some search engine also provide advanced search to customize the search process.

#### Meta Search Engine

There is no single search engine can cover the entire web. However, are there any search engines that will search several engines at one time? The answer is Meta-Search Engine.
A Meta-Search Engine is a special engine that sends user requests to several other search engines and aggregates the results into a single list or displays them according to their source. Meta-Search Engines enable users to enter search criteria once and access several search engines simultaneously.
Meta-Search Engine in nature is not a real search engine. It doesn’t compile a physical database or catalogue of the web. Instead, it takes a user’s request, pass it to several other databases and then compile the results in a homogeneous manner based on a specific algorithm. The most famous Meta-Search Engine is Dogfile.

#### Search Engine Optimization

Search Engine Optimization (SEO) become a hot topic in today’s Web. It is the process of improving the quality traffic to a web site from search engine via “natural” search results (compare with payable results). SEO is part of Search Engine Marketing (SEM). SEO experts consider how search engines work and what people search for. Optimizing a website will involve editing its content, redesigning its structure and improving its html codes to increase its relevance to specific keywords.

## How to Search Effectively

This part will introduce some specific skills to enhance students’ search power.

#### Search Engine Boolean Terms at a Glance

Most search engines and databases use Boolean Operators to create search queries. Boolean Operators include AND, OR and NOT. “AND” requires both terms should appear in the items that are retrieved. “OR” requires either terms appear in the items that are retrieved and “NOT” excludes a term. Use appropriate Boolean Operators can quick the searching process and target the search object precisely.
For more information, please review Google Search Basic.

#### How can I do an Advanced Search

Advanced searches can be done via search engines advanced search link. Google and Yahoo!, the most popular search engines, both support advanced search. We can access the page of advanced search directly from the homepage of search engines. Within the page, we can devise our queries and make them more purposely without knowing any search syntax. For example, we can require the content of the search results having or not having some words; or limit all the search results in a specific language. Furthermore, we can define the type of the search results – all the results are in the format of word, pdf, powerpoint or excel. For students, if they want to find some online learning materials, it is better to search documents with the extension of ppt and pdf since most class handouts are produced by Microsoft Powerpoint and Adobe Acrobat. These documents are usually useful.
If we know the type of file we want to search, we also can use specific search page within Google or Yahoo!, like Google Image, Google Video and Google book.
If we want to search some academic information, google scholar would be a helpful tool. It will search information from academic sources that include university (.edu site), research centres (NASA, RAND, etc), government, journal and book publishers, library collections and digital materials (e-prints, e-book).

#### Devising Search Query

Since search results is based on the query, the more precise your query statement, the more relevant materials you will find. The most common search pitfall is searching too broadly. In order to narrow down and give a specific search query, first we should be knowledge of the subject and know what we are looking for. Then try to develop specialized queries based on this knowledge. Don’t forget to use Boolean Operator and use quotation to limit the search to the exact phase. Although search engines look for the exact phase first, using quotation marks can limit it further. It is better to start the search with a reality check and be ready to change the query at any time. That’s, if the required results doesn’t turn up in the first ten or twenty hits, devise a new query and search again, and then devise another, and another.

#### How to Assess the Credibility of Search Results

Since anybody can post anything on the web, find information on the web sometimes is like being a police detective. Some website sites will turn out to be credible, while others will have evil motives. Please keep in mind, the information is only as good as the source. We should know how to evaluate the integrity of the information and to identify the relevant and credible sources.
When we access the “required” document via a search engine, try to find the answers for the following questions: Who is the author or sponsor? What authority do they have? What’s the purpose of the page? There are some tips can help us assess the credibility of a specific website/page.
* Does it include the author’s bio? Is there some information about this institution?
* Can the source be contacted, are they reputable?
* A tilde (~) may indicate a personal page and it always include some useful information.
* Check the domain section of the URL:
** .edu (educational) - tc.edu, more reliable, can be serious research but it also can be a student class project 
** . gov (government) - uscis.gov, usually dependable 
** . mil (military) – usually dependable 
** .net (network) – may provide services to customers 
** .org (organization) – unicef.org, often nonprofit institution, but sometimes it may be biased
* Is there a date of when the page was created or last update? Is some information obviously out of date? Do the links in the page work?
* Check the accuracy of the content: are there any biases, can the fact be verified, are there any citation from official source, what do other say about the author or organization?
* What’s the audience of the page? Is it intended for the general public or for a specific group (e.g scholar or teenagers)?
* What’s the tone of the page (serious or humorous)?
* If possible, try to compare and contrast related pieces of information from other sources (print and online).
Whatever, be careful to the web information. Learn to examine assumptions and possible biases, distinguish between fact and opinion. Think critically and don’t take the easy way out.

## Main Search Engines

The big four search engines are Google, Yahoo, Ask.com and Windows Live. None of them are comprehensive. Their results turn to be huge overlap, but still much that is unique. Each one has different ranking criteria, so the results ordered differently.
* Yahoo, Google’s largest competitor; rank results by popularity and relevance; have a link to the directory; have advanced search
* Ask.com, rank results by “Subject-Specific Popularity”; option of advanced search after running an initial search
* Windows Live, have great ambition; option of advanced search after running a initial search

## Understanding Error Messages

It is quite often that sometimes we are redirected to a bad link. We annoyed by this but can do nothing. Knowing the reason behind these familiar errors may make us feel better.
* Error 401: Unauthorised
* Error 403: Forbidden
* Error 404: Not Found
* Error 500: Internal Server Error

## Conclusion

There is no right and wrong for searching the Web. The only meaningful measure for a successful search is getting the results you desire as soon as possible. All search engines work differently. Your ability to find the information you seek on the Internet depends on how precise your queries are and how effectively you use search engines.

## Question

True or False:
* All the search engines use the same ranking algorithm.
* The principle of Meta-Search Engine is different from the general Search Engine.
* Information from the organizational website (.org) is more reliable than from the commercial website (.com).
* It is better to use broad query because it can turn up more results.
Short answer questions:
* What’s the general ranking algorithm of search engine?
* How can I use search engine to find documents in the format of powerpoint and pdf?
* What are the two types of search engines?
* How can I assess the credibility of a website?

## Answers

True or false: F, T, F, F
Short answers:
* Different engine work differently. There is no universal ranking algorithm. Google use PageRank to rank the results. Yahoo rank the search results by popularity and relevance. And Ask.com use “Subject-Specific Popularity” to rank the results.
* Use the advanced search links within the homepage of Google or Yahoo! You also can add search syntax to your query, like: American History file type: pdf.
* Key word search engine and directory search engine.
* Click here to learn more about the assessment of the web information.

## Reference

Alexander Halavais.Search Engine Society.Polity Press. 2009. Sandy Berger.Great Age Guide to the Internet. Que Publishing. 2005. http://en.wikipedia.org/wiki/Search_engine http://en.wikipedia.org/wiki/Metasearch_engine http://federatedsearchblog.com/2009/03/02/on-credibility-of-search-results/ http://www.mediapost.com/publications/?fa=Articles.showArticle&art_aid=101971 http://www.seochat.com/ Search Engine Optimization