So what's the difference between a Search Engine and a Search Directory ?
and How do they Work ?

It's important to understand the answer to both these questions because they need to be treated slightly differently.

A Search Engine.
There are generally two parts to a search engine, A Database and the Software which generates Search Results ( there is also a third part the Search Engine Spider - more about this in a moment ).

The Search Engine Database
A copy of each page on the internet ( that the search engine knows about ) is held within this database. The database does not hold all the images and other components ( eg. menu applets ) of that page but simply the HTML Code of that page.

Search Result Software
Each Search Engine has it's own result generating software, the details of exactly how they work are a closely guarded secret. However they all work in this general manner. When a user types in a keyword or phrase the software will read the database and pull out all the pages which are 'Relevant' to that keyword or phrase. It will then analyze each page and give each page a 'Relevancy Score'. The results are then sorted by Relevancy and then returned to the user with the most relevant appearing first.
Exactly how the software scores the Relevancy of a page is the Secret bit and is becoming more complex. But generally the software will take into account many factors including the number appearances of the keyword or phrase is such sections as,

• Title
• Page Heading
• Main Test Body
• Link Text
• Meta Tags

We go into this in more detail in the Page Construction section.

Search Engine Spider
This is a piece of software which essentially Navigates the Web looking for new pages to add to the Search Engine database. It does this by starting with a page already in it's database and following any links which appear on the page. It will then check to see whether it already has that page in it's database and if not it will add a copy to the database. If it does already hold a copy, it may also check to see whether the details it holds in it's database are the same as those of the real page, if not it will update the database with the new information.
As you can imagine with nearly a Billion Web Pages on the Internet this is no small task. One of the most efficient spider's around is that of the Google Search Engine. We see our pages spidered by Google once a month on a regular basis.

A Search Directory
Again there are generally two sections to a Search Directory, a Database and the Software displaying the results.

The Search Directory Database
This differs from the Search Engine database in that it doesn't store Web Pages, but rather some basic details about a web page. At a minimum these are,

• Page Title
• Page Description
• The Category
• Keywords
• and of course the URL of the page

And that's it !

The Search Directory Software
With most directories (and certainly all the major ones) the user has two options of finding the relevant pages.
Firstly they can simply browse down the Categories to find the Subject that applies to their query. Eventually a set of pages belonging to this category will be served up, generally sorted in Alphabetical order on the Page Title.
Secondly they can choose to use the Search Feature. This works like the Search Engine but rather than analyze the page in question for keyword relevancy, the 'Relevancy Score' is determined purely from the details held in the database, ie. Page Title, Description, Keywords and the URL.

Again, we go into this in more detail in the Page Construction section.

OK there it is, simple right ?
Well not quite, the world of Search Engines and Directories is now more complex and the distinction between the two has become a little blurred. Here's why, the larger Directories ( e.g. Yahoo ) and the larger Search Engines ( e.g. Google ) now also utilize each others databases when compiling the results for the user. Try it for yourself, do a search on Yahoo and you will also see some results from the Google database.

There is also a third complication, Pay per Click Programs.
These are search engines which generate two or three pages for each search on a participating Search Engine. Currently the largest Pay Per Click Program is run by Overture who supply results to ( amongst others ) Yahoo. The advertisers pay for this on a 'Pay per Click' basis, everytime a user clicks on their link they pay Overture a fixed fee. One assumes that Overture then pays Yahoo a proportion of this.
The 'Paid For Results' generally appear at positions 1,2 and 3 of the results.

So you're thinking,
"Can't I just skip all this Search Engine stuff and pay to have my pages listed at the Top".
Yes you can, but the Pay per Click programs are a 'Double Edged Sword' and although they can be very lucrative ( and therefor should form part of your strategy ) there are also dangers with them. So before leaping in, be sure to read All of this Guide,
it will Save You a Lot of Money !