The aim of this chapter is to clarify a group of related terms, including ‘argument attack’, ‘rebuttal’, ‘refutation’, ‘challenge’, ‘critical question’, ‘defeater’, ‘undercutting defeater’, ‘rebutting defeater’, ‘exception’ and ‘objection’, which are commonly used in the literature on argumentation. The term ‘rebuttal’ is often associated with the work of Toulmin (1958), while the terms ‘undercutting defeater’ and ‘rebutting defeater’ are associated with the work of Pollock (1995) and are commonly used in the artificial intelligence literature. The notions of argument attack and argument defeat are associated with a formal model of argumentation that is prominent in artificial intelligence called the abstract argumentation framework. As shown in the chapter, these terms are, at their present state of usage, not precise or consistent enough for us to helpfully differentiate their meanings in framing useful advice on how to attack and refute arguments. An additional difficulty is that argument diagramming tools are of limited use if they cannot represent the critical questions matching an argumentation scheme. A way of overcoming both difficulties is presented in this chapter is by using the Carneades Argumentation System.