What exactly is "Direct" traffic?

Direct Traffic can be one of many things. Here are a few possibilities:

1. Clicking a link from an email (depending on email provider/program)
   
   
2. Clicking a link from a Microsoft Office or PDF document
   
   
3. Accessing the site from a shortened URL (depending on the URL shortener)
   
   
4. Clicking a link from a Mobile social media apps like Facebook or Twitter (mobile apps often do not pass referrer information)
   
   
5. Going to a non-secure (HTTP) site from a link on a secure (HTTPS) site, as the secure site won't pass a referrer to the non-secure site. For instance, if someone clicks a link on https://example.com to go to https://example2.com, the analytics for example2.com will show the session as direct.
   
   
6. Accessing a site from organic search, in some instances, will end up being reported as Direct due to browser issues.