Google Analytics "direct" referrals

What is in this 'campaign'?

[teaperson]

I just started up with Google Analytics and my boss has some questions about the campaign source 'direct': does it include bookmarks? what about someone who sets us as their homepage? The number seems higher than I would have guessed for just typing in the URL.

[lethal0r]

some browsers do not set/can be set to hide the referrer field and perhaps these show up as direct. I couldn't give you figures on how many are like this though.

[teaperson]

I don't think it's that, because there's a category of "no referral" as well.

[alexdino1]

I believe it is the case where the visitor stayed on the page more than 30 minutes after being referred. This creates a new visit with the new visit referrer being "direct".