By theme relevance is meant that a site placing a connection to your site or the reverse should have a theme that relates with yours and not contrary to it. In other words your link partner’s website should consolidate whatever you offer on your site and not lessen its value or compete with it.
For example consider that you deal with widgets in your site, it’s only logical to allow links on your site that deal with widget accessories. Perhaps you are trading on SEO services; it’s advisable to get links handling articles that have to do with SEO, etc. It will make no sense for any of the aforementioned sites to incorporate links that are doing business in gambling or sports or porn, etc.
It doesn’t really mean that a buyer of blue widgets does not gamble or have interest in porn or other things. They do but while they are looking for the products and services on your site the chance that they would be interested in these other things is very remote. So it’s an unnecessary distraction.
In fact it’s in this manner that visitors of your site would normally think and it’s, as well, the way Google or Yahoo! or any of others consider it to be. Popular search engines such as Yahoo!, Google, etc have a common goal and that is customer satisfaction and that entails providing accurate and relevant search results to their users. They may differ in algorithm but this is an underlying principle that is not subject to change.
Currently results from Google, involving all kinds of links or positions in the Search Engine Result Pages (SERPs), confirm the aforementioned points. These results show that there is an importance attached to theme relevance.
Google’s algorithm used for the mathematical calculation to determine a site’s position in the search results has been revised to include theme relevance. This affects not only search results found in SERP but also page rank and link valuation formulas.
Website owners should look for solution to theme relevance problems and that lies in simply having theme and topic-related content and links with the same characteristics as mentioned above.