While having someone link to your site might drive traffic
if they visit your site from a link on that site, having links
that are not relevant to the content on the linked sites on
your site may actually harm your ranking on the search engines.
Search engine positioning on sites
like Google are based on a point system. This system adds
or subtracts points to or from you for various reasons.
For example it used to be that if you hid keywords on your
page repeated over and over, you moved up in the search
engines on a relevance basis. This practice over time became
known as a form of "spamming
the search engines". When you have hidden text on your
page (hidden text is when you make the text the same color
as the background so it is invisible to the user) you lose
points in the rankings and move down the list.
Search engines have been made very intelligent by their creators.
They do things like compare the keywords to content, look
for content changes, and compare the content of site links
contained on the site to the sites they link to. If the content
is relevant to the site chances are it helps your site rating.
If the links are not related, it can hurt your ranking.
It seems then that to have effective linking we should only
link to sites that contain complimentary content. If I have
a business site, my site should link to other sites with business
content. To link my site to a beauty salon site would probably
do very little good for me as far as traffic is concerned
and would very likely be detrimental to my site ranking.
Now I do not want to deter you from having advertising on
your site. Ads are a different animal. Links usually are all
grouped together on a page of suggested links while ads are
usually mixed in with the content and take the form of banners.
These types of ads will not hurt ranking. Most profit driven
web sites have some form of ads on their site and the search
engines are made to take these ads into consideration.
To sum it all up, links are good only to sites that are relevant
to your content. If someone asks you to do a link exchange
that is not relevant to your site, thank them for the offer
and decline politely. If their content is related to yours
be sure to make it happen if you have a way to do it.
As a web master who enjoys a top 5 listing on most search
engines on the internet I can say that when it comes to learning
how the search engines work it is better to have linked and
lost than to have never linked at all. ;-)