The term was first used by Internet theorist John Kilroy in a 2004 article on paid search marketing. Because the distinction is important (and because the word "organic" has many metaphorical uses) the term is now in widespread use within the search engine optimization and web marketing industry. As of July 2009, "organic search" is now common currency outside the specialist web marketing industry, even used frequently by Google (throughout the Google Analytics site, for instance).
If you’ve recently modified your on-page copy, undergone a site overhaul (removing pages, reordering the navigation) or migrated your site sans redirects, it’s reasonable to expect a decline in traffic. After reworking your site content, Google must re-crawl and then re-index these pages. It’s not uncommon to experience unstable rankings for up to a few weeks afterwards.
Beyond organic and direct traffic, you must understand the difference between all of your traffic sources and how traffic is classified. Most web analytics platforms, like Google Analytics, utilize an algorithm and flow chart based on the referring website or parameters set within the URL that determine the source of traffic. Here is a breakdown of all sources: