In this book, I refer to activism as a collection of social and political phenomena. Though rather general — many things can go under "activism" in my definition — activism cannot be just any social or political activity. I have no urgent claim to the objective validity of my definition of activism (see the following paragraph), and would only like to delimit or define as well as possible the field of phenomena this book, and this chapter, deals with. Here are some of the features that I have in mind when I think of activism.