The papers published by the Revista about Evidence-Based Cardiology (EBC) have, so far, discussed general aspects of the theory as well as practice of EBC, using simple terms. We need a detailed description of the general, as well as specific, concepts applicable to EBC, in order to understand this methodology better and to facilitate the reading. In this first article we present a glossary of terms applicable to general aspects of the methodology, including terms found in papers about diagnosis, treatment, risk/harm, etc. A second paper, to be published in the next issue of the Revista, will present concepts regarding clinical trials (types, methodology, etc.) and systematic reviews.