What is organic traffic and how to get it?

A.1. Organic Traffic - It refers to the users who searches on Google and as per search they will click on blog or website.

A.2. If the traffic comes via social network like Facebook, it is Social Traffic. So, It won't considered as Organic Traffic.

A.3. If the traffic comes via forums post, it is Referral Traffic.

A.4. IF any of your keyword ranked on Google, surely you will get Organic Traffic. Social Network, Forums helps your blog to rank on Google. Link Building is must for the blog or websites.

In short, organic traffic refer to natural traffic that comes directly from search engine only and not from any other sources including internal or external links etc.

Q.1. What exactly is the meaning of organic traffic?

A.1. The traffic to webpages that comes via search engine only upon using the keyword input by the visitors which the page get indexed to reach the web.

Q.2. Would traffic to a blog which comes via a social networking site (such as Facebook) be considered to be organic traffic?

A.2. No, not at all. It will be called as referral or social traffic.

Q.3. If I share a blog post at a public forum and traffic from there comes to my blog, would it be considered to be organic traffic?

A.3. No, not at all. Again, it will be called as referral traffic.

Q.4. What are the various legitimate sources for organic traffic if neither social networking sites nor public forum are the valid sources?

A.4. Only the best written and quality content which search engine crawls, stored and index the related keyword or topic on visitors' search.

In a simple words, If you are getting visitors to your websites by 'search engines', the corresponding traffic is called 'organic traffics'. When you invite others via social networking, it is not considered as 'organic traffic' as search engine does not play role in it.

In my opinion, if you have written genuine article with some good keywords with catchy title, you even do not need social networking sharing. Organic traffic will follow you!

Below are answers to your questions:
Traffic from search engine like google is listed in organic traffic.
Traffic from social sites is not organic traffic.
Traffic from forums may be unique or not depend upon keywords.