Link building is an art of earning high quality links from other authoritative websites in order to improve a website’s visibility in Google search results. In Oct 2014 the Penguin update crushed thousands of websites for their low quality and unnatural link building practices.
Before the inception of Penguin update, SEO was only limited to creating links without consideration of quality and authority. But the traditional low quality link building tactics are no longer beneficial to get positive results in 2015.