In this chapter we will examine the four major issues that influenced our design of the collaborative filtering system. We start by examining the issue of accessibility and who has access to a user's votes. We move on to the key issue of distributing vote information in a fashion that imposes minimum overhead on the Net News system. We continue by noting social conventions of Usenet that constrain our design. Finally, we end by searching for patterns of user behavior that quantify the troubles users have searching for interesting articles.