My mentor, Roy Williams, described shoppers as operating in either one of two modes: transactional or relational, a few years ago. At that time, some of us loafed around virtually, exchanging emails with friends, trying to complete a list of reasons that motivate people to buy things. (Thank you, Tom G. and Brett F.) More recently, I returned to compiling the list with the rest of my colleagues. Trying to understand these types of things is what drives us. It also benefits our clients.