A User Name and Email address are required. The US Zip Code field is not required, but essential for facilitating local networking for US residents, where that is desired. Likewise, the public email is not required (except for organizers), but (currently) essential for email communication by any users of this website amongst themselves. (I.e., the public email is to allow you to be contacted by anybody other than us.) It can, however, be the same as your private email. You may want to create a new email account to serve as your public email. A popular, free email provider is gmail (google).