Search Engines - Subject Directories

SEARCH ENGINE vs DIRECTORY SYSTEM

This is an issue which confuses a lot of people. So perhaps it would be best to define the primary differences here and now, thus clearing up any confusion you might have.

Search Engine- A search engine is a database system designed to index internet addresses (URLs, usenet, ftp, image locations etc). The typical search engine contains a special program often called a spider (also sometimes called a "bot" or "crawler"), the spider accepts a url, it then goes to that website and retrieves a copy of the file found there. Sometime later, it the search engine will process that copy of the file, distilling it down to the bare essential data it needs for the database. While most search engines request both a url and an email address, the search engine makes the determination as to what data ends up in the database. In short, given a url, an automated process occurs which results in your site being  included into the index.

Directories- A directory is basically a manual entry database system. You, as the end user submitting your  url, will supply the directory with all of the needed  information during the submission process. At a  minimum, this information includes, url, title and a short summary of your website. Rarely will the directory have any program capable of visiting your website, although a few directories do have a simple spider capable of verifying that the url you provided was a valid URL.

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While both classes of systems have elements in common, such as the ability to search the data base, boolean expressions, and advanced features. The primary distinction lies in how the two systems obtain their data. One does it automatically (search engines) and the other does it manually (directories).

Search Engines

are robot-driven and so are able to index a huge amoung of information on the Web. This is why they often contain a lot of rrelevant information and it can be difficult to sift through the rubbish to find quality pages. Search engines are far more comprehensive than subject directories.

Subject Directories

are structured hierarhically are filtered by people who decide to include or exclude.  They are very good at  finding information on general topic and are excellent starting points for locating Web sites. Many subject directories are also searchable.

Meta-Search

tools search multiple engines and subject directories simultaneously. Meta search tools are useful when you are wanting to fo a fast search to find something relatively simple. This means that the results are not as comprehensive as when you search the searach engines and subject directories individually.

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