Silken is the authorisation service in operation on this site, handling visitor registration, linking to external OAuth authorities and determining the "eligibility" of visitors. This eligibility may be used to, e.g. permit / deny access to various areas of the site.
To perform its task, Silken requires the site to set one cookie (SilkenID). This cookie is used to identify you purely for the purposes of letting the site know your eligibility. It is not used to track your activities or violate your privacy in any way.