G considers more than just a site's name for relevancy

If you have the patience for a long read, check out some of the math behind G's algorithm:

PageRank Algorithm - The Mathematics of Google Search

Sorry I couldn't put it into more layman's terms

Jaggyjay is right, there is a lot to explain about this, but there is a whole lot more involved in googles algorithm.

Google knows and sees everything [/JK]

No one really knows all the inner-workings of their algorithm but I will venture to say that they do not look at niches when determining relevency but rather broader industries. So if a given page is about herbs they will categorize that page in the agricultural industry. There could even be an overlap in indutries as well... the page about herbs could also fall into the food and beverage industry.

With the amount of data they have they will be able to look at certain words on a page and instantly categorize that page!

The type of backlinks, the pages they originate from as well as the anchors will also help determine the overall relevency of a page.

I would not kill myself trying to get backlinks from strictly herb-related sites but even if the site is partially related the link will still carry weight. But the authority of the site you are getting your link from will still carry weight.

Hi,

As per your example below, if Apex.org was a relevant backlink then Google would search their site and look at how many and the quality of incoming and outgoing links they have.
Not only that, a backlink from a site that has nothing to do with your site is not necessarily irrelevant. If a car racing site with a high PR rating sends a backlink to a health site, it is also considered by Google as a valuable backlink. As long as the health site does not have to many High PR backlinks and it doesn't seem fishy then it's ok.

Obviously you would have your keywords in H1, anchor text and meta tags and thats how Google would know what your site is about and and if your backlinks are relevant or not.

Although SEO takes a long time to master, I think it is always important to have a site well optimized especially with the way Google keeps changing its algorithms. Hope it helps.

Mo.

If your doing manual posts I would not worry about strictly in your niche but rather the quality of the page your leaving your link on.

Yes, if both the websites are having valuable backlinks and high PR then Google will must find out some relevancy at some instant.

Google use Latent Semantic Indexing (LSI), which helps to recognize the niche of any website by understanding its content. I hope now you know how Google decide relevancy.