In the broadest possible sense, responsibility is “but a set of practices that we use to describe and understand individual and social behaviour” (French, 1992, p. IX). In order to understand how we can use the term as a description and what results from the description, one must be aware of possible definitions, implications, dimensions, conditions, etc. In this chapter we will therefore attempt to describe all these different features of the word. In a first step we will look at the overall definitions that can be found in the literature and the implied objectives of its use. This part will also contain a first reflection on how responsibility relates to ethics and morality. The next part of this chapter will analyse the conditions that are commonly named for the ascription of responsibility. This will then allow us to discuss the classical dimensions, namely subject, object, and instance. From there we will proceed to take a look at the other relevant determinants of responsibility such as type, temporal dimension, sort of imputation, and the limits of ascription. As a summary we will extract the implications that most sorts and definitions of responsibility share. In total this chapter will lay the theoretical groundwork needed for addressing the problems that responsibility in information systems pose, which will then be discussed in the following chapters.