However, in the eyes of Google, a backlink is still seen as a vote of confidence from a 3rd party in the target website's relevance and authority on a given topic.
Whereas in the old days an abundance of back links to a website could almost guarantee it ranking well in the search engines, Google now has the ability to dissect and analyse that backlink, look at the relevance of the content surrounding the backlink and that the relevance of the website that the backlink comes from and based upon its own calculations it will value that backlink accordingly.
In the good old days, Google would simply look at the anchor text and then credit the target site with the relevant backlink for that word or phrase. But as the backlink system became abused by enthusiastic SEOers (who me?!), Google realised that it had to take more factors into consideration and expanded its algorithms to look at the relevance and quality of the website the backlink was placed upon.
It also looked at the content surrounding the backlink for both quality and relevance and also started to take a step back and look at the overall pattern of the backlink's pointed at the target site.
It then started to recognise and punish unnatural activity. This is what defeated the old SEO tactic of "keyword stuffing". It didn't take Google long to work out that it was not a natural occurrence for all, or even a very high percentage of the backlinks, to have the same anchor text.
So now the current definition of a good backlink is a little more complex. The site that contains the backlink needs to be of good standing in the eyes of Google with decent quality content as well as be about the topic that is relevant in some way to the website the backlink is pointing at.
Not All Backlinks Are Equal
Part of a Balanced Online Marketing Strategy
Press Release Link Building
Backlink Building Strategies
So as we can see, as the link building process continues to grow to be more complex and to avoid doing more damage than good to your website through collecting spammy links, overuse of keywords in your backlinks anchor text, broken links, it's extremely important that you have a well thought out online marketing plan for your website.