Link building has always brought up the most questions and confusion for clients when it comes to SEO. Link building is not dead, it has just evolved.
Not too long ago, Google announced that irrelevant, low quality links would not help in digital marketing efforts; but it may hinder them. Google and Matt Cutts put their efforts together to help clean up the "black hat" efforts of some internet marketing companies. Link building is a strategy that works and should be a crucial part of any internet marketing strategy.
Relevance Is Key
Any link strategy should contain resources that are in a similar industry as you. Example: A landscaping company can contain links from hardscape material suppliers, lawn care organizations, etc. Keep in mind that search engines can take this relevance into consideration with not only your anchor text, but your description as well.