A while back I talked about how Google cares about inbound links when it comes to SEO. What I didn't mention is how not all links are created equal. As with all SEO topics, this can be kind of complicated, so I'm going to start by talking about anchor text.
Anchor text is the text that shows up in a hyperlink. For example, the anchor text for the link in the first sentence of this post is "Google cares about inbound links when it comes to SEO". Many people don't realize that when search engines come across links pointing to your site, they pay close attention to the anchor text of those links. The anchor text probably describes your site, and so search engines associate those keywords with your website.
Here's a pretty funny example of anchor text affecting SEO in the real world. A few years ago if you searched for the word "Exit" on Google, the top result was Disney.com. That seems very strange since Disney doesn't really have anything to do with exiting. So what happened?
It turns out that adult entertainment websites were single-handedly responsible for Disney.com's #1 ranking. There were thousands of porn websites that had a landing page verifying that visitors were 18 years old. There were two links: "Enter" (which took you to the adult site) and "Exit" (which went to Disney.com). Because thousands of porn sites linked to Disney.com with the word "Exit", Disney.com became the #1 result on Google for that search term.
Hopefully that demonstrates just how powerful anchor text can be. Now the question is why you should care. Obviously you can't always control the anchor text people use when linking to your site, but you should do everything you can to pick the right keywords when you do have a say.
For example, let's say I want to link you to my personal portfolio website (which is horribly out of date) from this blog. If I didn't know to pay attention to the anchor text, I'd probably use something like "Go check out my blog". However, for SEO purposes, it would be much better to instead say "Check out my blog about software development and design". The second link will encourage Google to associate valuable keywords with my website.
Armed with this information, I encourage you to not only generate inbound links to your website, but also use whatever tools you can to make sure the anchor text is sending Google the right signal about your site.