Friday, July 12, 2013

An Introduction to Search Engine

In the last unit, we explained why search engine visibility is important. In this unit we will take closerlook at search engines. Because SEO is about improving the visibility of your web pages in search engine results, we have to understand a bit about how search engines work. By the end of this unit you should be able to: Understand what search engines do

1. Understand which search engines to concentrate on when optimizing your site
2. Understand how search engines rank results
3.  Measure the Page Rank of individual web pages
4.  Understand how to perform advanced searches

This unit assumes that you have read and understood the last part of the course and that you are comfortable with the terms: keyword, key phrase and search engine optimization.What is a search engine? Wikipedia defines a search engine as: „a program designed to help find information stored on a computer system such as the World Wide Web, or a personal computer. The search engine allows one to ask for content meeting specific criteria (typically those containing a given word or phrase) and retrieving a list of references that match those criteria. Search engines use regularly updated indexes to operate quickly and efficiently.‟ In other words, a search engine is a sophisticated piece of software, accessed through a page on a website that allows you to search the web by entering search queries into a search box. The search engine then attempts to match your search query with the content of web pages that is has stored, or cached, and indexed on its powerful servers in advance of your search. Many search engines allow you to search for things other than text: for example, images. However, for the purpose of this course, we will focus on text-based searches. As we pointed out in the last unit, SEO methods are largely (but not exclusively) centered upon text as they involve matching key parts of the text in your web pages with the keywords or key phrases that people actually type into search engines when looking for something on the internet. There are two main types of search indexes we access when searching the web:

(a) Directories
(b) Crawler-based search engines


Unlike search engines, which use special software to locate and index sites, directories are compiled and maintained by humans. Directories often consist of a categorized list of links to other sites to which you can add your own site. Editors sometimes review your site to see if it is fit for inclusion in the directory.

Crawler-based search engines

Crawler-based search engines differ from directories in that they are not compiled and maintained by humans. Instead, crawler-based search engines use sophisticated pieces of software called spiders or robots to search and index web pages. These spiders are constantly at work, crawling around the web, locating pages, and taking snapshots of those pages to be cached or stored on the search engine‟s servers. They are so sophisticated that they can follow links from one page to another and from one site to another. Google is a prominent example of a crawler-based search engine. Note: Some search systems are „hybrid‟ systems as they combine both forms of index. Yahoo, for example, features both directories and search engines. As we will see later in this course, the SEO process often involves optimizing your site in such a way that it allows search engine spiders to locate every page on your site quickly and easily Spidering vs submitting your site manually. If you browse the web, you will notice that many companies will offer to submit your site to search engines for inclusion in their listings. The services these companies offer are largely unnecessary and can prove to be a waste of time and money. It is important to remember that search engine spiders are constantly crawling the web, following links and indexing pages. Because spiders automatically index your pages when they find them, there is absolutely no need to submit your site manually to the major search engines. Note, however, that the process of being found can take some time, and it can be weeks before the major search engines index your site. SEO is a cost-effective way of making your site visible, but it can take time especially for new sites. However, there are ways to accelerate the indexing process which include xml site maps and RSS. Both these topics will be covered in the next tutorial.

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