Organic traffic is the traffic that comes from accessing the site from visitor searches on Google, Yahoo, Bing, or other search engines. It is that traffic that you get "naturally" and most desired of all. This traffic is targeted, those who come to the site come after searches by keywords or expressions that are related to the topics addressed on the website.
Backlink is a link one website gets from another website. Backlinks make a huge impact on a website’s prominence in search engine results. This is why they are considered very useful for improving a website’s SEO ranking. Search engines calculate rankings using multiple factors to display search results. No one knows for sure how much weight search engines give to backlinks when listing results, however what we do know for certain is that they are very important.
Backlinks should be natural, this means that a website must not use artificial ways to create backlinks for their own websites. The quality of links is far more important than the quantity.
In order to drive traffic through organic search, you need to optimize your web content for organic keywords. Those are the terms that people are typing into Google in order to find information and solutions to their problems.
Although Google's ranking algorithms include many, many factors, and the algorithms are always evolving, one of the leading factors is on-page keyword optimization. If the keyword that people are searching for doesn't appear anywhere in your web copy, you are highly unlikely to rank for that keyword.