SEO and The Value of Leaving Blog Comments
If you are a blogger or a webmaster who is looking to increase your sites relevance in the top search engines by stuffing comments with links to your blog there is one simple fact—you're barking up the wrong tree!
While there are a lot of misconceptions about how the spiders, which are at the heart to search engines work there is one simple truth that is often over looked: webmasters can control where they don't want a search engine to look. First most engines reference a robots.txt file which can contain rules about where search engines should not go, and most search engines will respect the file to improve their own efficiency. Next embedded within an anchor tag there is a relationship attribute (designated as "rel=") that allows a webmaster to identify a link as external and to indicate "nofollow" for a search engine. While this isn't necessarily a problem comments on nearly all popular blog software contain nofollow link rather than traditional links, which means that all popular search engines will ignore the links in comments for the purpose of identifying link popularity and link relevance.
So this raises an important question:What is the value of leaving blog comments?
Once you get beyond the technical reason why leaving comments to game Google doesn't work the obvious answer emerges—to participate in a community. Leaving comments and relevant links helps the blogger and the other commenters to find other interesting and relevant information. Since you are discouraged from posting irrelevant information as a blogger who is participating the community you gain the opportunity to gain "natural readership" but proposing value before the guest arrive.
I compare this to a mechanic overhearing individuals talking about a squeak on the front passenger tire and offering to explain the possible causes of the problem then concluding the conversation with saying, "By the way, we can schedule an appointment to take a closer look if you would like." Value was added before a sale was made—just like a bloggers participation in the community.
Don't look for blog comments to be a one way interaction to get you what you are looking for—more visitors—rather look at them as an opportunity to improve the collective community and enhance what you can bring to the relationship.