Hey Ashok! Good question. I work with clients in a lot of different industries, so the tactics I employ are often quite different depending on the client. In general though, creating killer resources around popular topics, or tools related to client services. This provides a ton of outreach opportunity. For example: We had a client build a tool that allowed webmasters to quickly run SSL scans on their sites and identofy non-secure resources. We reached out to people writing about SSLs, Https migration etc and pitched it as a value-add. We built ~50 links to that tool in 45 days. Not a massive total, but they were pretty much all DR 40+.
To give you an idea of just how much money is being spent on paid search, take a look at Google. Google's AdWords program is the most used pay-per-click (PPC) advertising program available today. While the tech giant owns YouTube and Android, among hundreds of other profitable brands, AdWords accounts for roughly 70% of their revenue -- which speaks wonders for its effectiveness.
The term “organic traffic” is used for referring to the visitors that land on your website as a result of unpaid (“organic”) search results. Organic traffic is the opposite of paid traffic, which defines the visits generated by paid ads. Visitors who are considered organic find your website after using a search engine like Google or Bing, so they are not “referred” by any other website.