What
are search engines and directories?
Directories
are databases of web sites that are created by humans. Yahoo! is
probably the most famous directory. The largest directory is the Open
Directory Project (DMOZ)with over 3.8
million sites. Directories determine ranking based on the submission
procedure
and
how a site looks to the human who visits it. The submission procedure
is the key to how a web site is ranked. The web designer who wants
his/her
site listed in a directory submits a short description to the directory
for the entire site, or editors write one for sites they review.
A search
looks for matches only in the descriptions submitted.
What
kinds of things can be done to give a web site a high ranking?
Search
engines grade sites on a point system (a ranking algorithm). The actual
algorithms both change frequently and are trade secrets. The ranking
is based on the content of the pages themselves (both text and code)
and the link popularity of the site. The directories using humans to
catalogue and rank websites use the actual text on the page and the
depth and richness of the content to determine ranking. However, many
of the search engines and directories have partnerships where they use
each others databases to supplement their own. The result of this system
is that some of the largest search engines and databases are actually
hybrids of search engines and directories.
What
do search engines use to rank a web site?
Code
There are certain items in the code of a web site that influence where
a site is ranked on a search engine or directory. Those are the URL
(universal resource locator or web address), the title, meta tags(keywords
& description), alt tags and comments. These are in the HTML code
most of which are invisible to users but not search engines.
Example:
URL:
www.groupexercise.com
<TITLE>Personal Trainer and Group Exercise Classes</TITLE>
<META name="keywords"
content="group, exercise, classes,”
<META name="description"
content=”Group exercise classes and personal training for increased
performance and better health.”>
<IMG SRC="images/group_exercise.gif" WIDTH=100 HEIGHT=100
ALT="gymnastics photo">
Comment:<!—The following is a table comparing
different group exercise classes -->
