Organic traffic : is those visitors that land on your website from unpaid sources, aka essentially free traffic. Organic sources here include search engines like Google, Yahoo, or Bing.
The brand of digital marketing that focuses on improving organic traffic is called Search Engine Optimization. Organic traffic increases website trust and tends to have better conversion rates than paid traffic because there is a better intent for organic searches. The ROI for organic traffic is very high since it is semi-permanent in nature compared to paid ads.
There are more than 255 factors that contribute to organic search rankings but the most important ones are: providing the correct and updated content to the searches, using relevant keywords, and acquiring clicks from other high ranking websites.