While people love to talk about link popularity and
search engine rankings, they rarely talk about one
of the more common problems with link building. In a
nutshell, unless the links to your site exist on the
first or second directory level of the linking site,
they likely won't impact search engine rankings.
The technical term for this is "link depth origination".
A search engine's crawler/bot indexes your web site
(or anyone else's) only to a certain depth and then
moves on to the next site. The depth a search engine
crawler will go varies from engine to engine and even
varies for the same engine from day to day and URL to
URL. However, most crawlers go no deeper than three
directory levels into any given site, like this.
(yoursite.com/level-1/level-2/level-3/).
In looking at your server logs, you may find instances
where a crawler has gone deeper than level 3, or shallower,
but the point to take away from this is if a link to
your site is on a page on the originating site that is
deeper than the third directory level, the crawlers will
never know the links exists. The link is deeper than the
crawler crawled.
Not to mix metaphors, but imagine fishing on a lake
that's 100 feet deep with a net that can be lowered
only to a depth of 50 feet, and you get the picture.
Anything that's deeper than 50 feet is not going to be
caught by the net.
This does not mean that such links are worthless. It
means only that such links cannot be factored by the
engines into the engines' link popularity measurement.
They can't factor what they don't know exists.
This raises an intriguing scenario. Imagine you have
two sites with nearly identical content. Site A has
500 sites linking to it, but all 500 sites placed
those links beyond their third directory level.
Site B has 25 sites linking to it, all of them at
the highest (top) level directory.
Which site, A or B, is better positioned from a
linking standpoint?
Well, it all depends. What kinds of sites do the links
exist on? Those 500 links to your site will be useless
if they originate on random link lists with no content
and no page views, or if all those links were beyond the
third directory level on the originating site. Likewise,
site B with only 25 links may be getting nice new
traffic if all 25 links originated close to the surface
(top level) of well-trafficked, topically relevant sites.
This is an extreme scenario. It's more likely that your
site falls somewhere in between. You have some good links,
and you have some useless ones. You usually can't control
where the originating site places its link to your site.
If I have a links page that is four directories deep on
my site, then even if it's the most useful links page in
the world, none of the search engines are going to find it.
Let's sum all this up in a list of key points.
- If your goal is to improve link popularity, the
links to your site need to originate as close to
the top level on the originating site as possible.
- A link originating beyond the third or fourth level
is still important if the originating site is topically
relevant and useful. Yahoo! is a good example. Most
sites linked by Yahoo! originate far beyond Yahoo!'s
third directory level. My own Yahoo! listing is five
levels deep, yet sends me hundreds of visits every day.
- A few purposeful links are better than many non relevant
laundry list link lists or Free for All Links Pages.
| 
The Small Business Guide