To become an evidence based practitioner and utilize the evidence hier­archy, clinicians should begin by asking questions, since good questions prompt searches for high quality answers. In general, clinicians should ask questions of themselves, questioning even common practice and of consultants, demanding evidence in support of recommendations. They can then begin looking for answers at the highest possible point on the evidence pyramid and move down if no evidence is found. The starting point to answer a given question depends upon the nature of the question. For Background questions, which relate to basic information about a topic, it is best to go first to evidence-based topic summaries. An exam­ple of a background question is “How is thrombotic thrombocytopenic purpura (TTP) treated?” Foreground questions are specific, concerning, for example, the impact of a certain treatment on a particular outcome in a specific patient population. Answers to foreground questions might be found in topic summaries if they relate to an issue which has been addressed by many studies, but if the issue is less well studied it might be better to start with systematic reviews or summaries of individual studies. An example of a foreground question is, “In young women with TTP, does plasma exchange improve mortality as compared with treat­ment with steroids?”