...In fact here's an example of how I might use it for my client's benefit...
Let's say for example my client is an Arborist. Someone searching for that type of service will more often than not be aware that there are municipal bylaws in place for protection of trees. So, realizing that those potential customers of my client will be browsing municipal bylaw pages I go to that municipal page and analyze the copy written content. Then on my client's page I will write the content in such a manner that the "common ground keywords" that are prevalent on the municipal site are also included in the text I write on my client's site and also link out to the exact municipal page that answers the question the searcher needs answered.
This creates a wonderful effect of nudging my client's page up to the top with the "authority" municipal government page and frequently, as long as the searcher is attentive, they realize their "luck" that not only have they found their answer but also; "oh look lucky me there's even a result to a company that offers the exact service I'm looking for and now won't have to go looking for that too".
Sweet example of Website Optimization. There are MANY MANY ways of improving ranking without ever turning to getting offsite links and social media.