Search Engines vs Directories

 

How do search engines differ from subject directories?

Self-Test

If you can search a subject directory, does that make it a search engine?

Test yourself:
Click in radio button to select your answer, then click on Check.

Yes
No

The key difference between a subject directory and a search engine is that the search engine indexes the content of the pages at a site, whereas the directory merely carries the name of the site, a short description of the site, and the category into which it has been classified.

O Oysters
Take Lewis Carroll's poetry as an example.

At Yahoo! Directory we can find listings for Lewis Carroll and his works in the category -- Arts > Humanities > Literature > Authors > Literary Fiction > Carroll, Lewis (1832-1898). Clicking through on several of those links will take us to collections of his prose and poetry.

But if we are looking for the line from Carroll's Walrus and the Carpenter, "O Oysters, come and walk with us!" it is better to use a search engine.

Yahoo can't find the poem in its subject directory but it does find it in a web search. (O Oysters come and walk).

Recap

Subject directories link to the first page of a major content area.

They index only the title, url, and description - NOT the words on the page.

There are some exceptions.

  • Yahoo will classify pages down to the product level for a fee.
  • Open Directory often indexes articles or single pages on a subject - as does Looksmart and Yahoo.
  • Google indexes the text of the pages in the directory it takes from Open Directory.

Search engines collect many pages from several levels of a Web site (each search engine has its own policy). Search engines provide us with the ability to search for actual words on pages.

Regrettably, search engines do not necesssarily index all pages of a site.

In most cases depth of indexing is only two levels down, although Google and Yahoo have agreements with some sites to "deeply" index them.

Also, search engines don't index all words on a page.