Basically, link building is a way of getting "votes" from other authority websites to boost your position in a Google, Yahoo, MSN search for a specific keyword phrase e.g. "Hairdressers in Barcelona", if that was your business.
Google likes it when you have authority links coming to your website and the better quality they are, the more Google trusts your website. The end result is that you move up in the search engine rankings and more people will find you for your keyword phrase.
