It's pretty important to keep track of who you're sharing your information with. This site keeps track of the following pieces of information:
Your email address
Your phone number (required before you submit a lot)
Your mailing address (required before you submit a lot)
We don't collect or store any sort of payment information at all. For the most part, your contact information isn't shared with anyone else on the site. Here are the only times your information is shared with other users:
Your email address is visible to all users on your contact page, unless you hide it in preferences. Users that aren't logged in can't see any of your info (except your username) at any time. (I have noticed that some of you use your email address as your username, that will be visible to non-logged-in users.)
When you confirm your pickup location for an auction, all of your contact information is made available to the organizer of the auction. This is visible to them even if you don't sell or buy any lots in the auction.
When you sell a lot that is part of an auction, your real name is given to the winner of that lot.
When you win a lot that is part of an auction, your real name is given to the seller of that lot.
When you sell a lot that is not part of an auction, all your contact information is given to the winner of that lot.
When you win a lot that is not part of an auction, all your contact information is given to the seller of that lot.