When it comes to SEO, there are a lot of moving parts involved that will help improve your site in the search rankings, some more important than others. One of these parts, that until recently played a major role in a site's ranking, was called "back linking". This is where people would basically try and put a link directing a visitor to their site on as many other sites as possible. The theory was that the more links out in the world that go back to your site, the higher up in the search engines your site will be. Like a fisherman casting out as many lines as possible anywhere on the water, with hopes that he will catch more fish. Despite the fact that fish might not even be where all of his lines are falling. There are many SEO companies out there that provide this service, however, due to Google's recent modification to their ranking algorithms, a lot of these back links are now no longer considered relevant. Like fishing lines falling in fish-less waters. Even worse, a lot of these back links are now considered to be "spam" links and can actually hurt your site rather than help it.
So, why did Google decide to do this? The answer is pretty simple... Google cares about providing their users with rich content that is relevant to what their users are searching for. They could really care less about how popular a site is or about how many spammy useless back links it has. So when it comes down to it, for people that have websites with interesting and original content, this is definitely a good change that will help them share their content and get discovered. I'm not saying you shouldn't worry about back linking to your site. But rather focus on having "quality back links" and quality, interesting, and original content, so that your site is a tool that allows you to engage with others. If your content is interesting, people will find it, share it, and your site's rankings will climb.