The aim of the Cochrane Library is to prepare, maintain, and promote the accessibility of systematic reviews of the effects of healthcare interventions. It contains 4 databases: the Cochrane Database of Systematic Reviews (CDSR), the Database of Abstracts of Reviews of Effectiveness (DARE), the Cochrane Controlled Trials Register (CCTR), and the Cochrane Review Methodology Database (CRMD). They all use the same search engine. The Cochrane Library The CDSR contains systematic reviews that are prepared by using explicit criteria for searching the literature and for appraising and synthesising the retrieved evidence. Evidence is included or excluded on the basis of quality criteria to minimise bias. These reviews focus on issues of treatment and thus primarily include randomised controlled trials. 47 Collaborative Review Groups are currently working on reviews. Each systematic review contains an informative abstract; detailed descriptions of the objectives, study inclusion criteria, search strategy, study methods, …