Despite five decades of intensive research, mechanisms initiating and stabilising atrial fibrillation (AF) are still not fully understood. Nevertheless, mapping studies, next to clinical trials and research on cellular electrophysiology, have provided key information that has led to a much more profound understanding of the arrhythmia. Contact mapping using multi-electrode arrays (MEAs) is the gold standard for high-resolution mapping in basic research and clinical trials, and continuously contributes to a better description of mechanisms perpetuating AF. It thereby provides information needed to target and test new pharmacological and interventional treatment options for AF therapy and to evaluate established ones, which were often implemented based on purely empirical assumptions. In patients undergoing cardiac surgery high- resolution contact mapping studies are performed for basic research purposes to evaluate to which extent data derived from animal models of AF is comparable to data recorded in humans. The goal of these research projects is to develop algorithms that allow the identification and staging of the arrhythmogenic substrate. This information should then help to guide surgical therapy when applicable, or individualise treatment strategy involving catheter ablation, antiarrhythmic drug therapy or simply a rate control strategy. Mapping techniques used in the catheter laboratory by interventional electrophysiologists represent a valuable tool for exact localisation of catheters and the points of interest for ablation. These techniques integrate data on individual anatomy (derived from CT scan or intracardiac ultrasound), local intracardiac electrograms (re-corded point by point with a catheter) and the exact spatial position of the catheter. While mapping techniques used with electrophysiological studies and ablations in patients are highly useful tools to optimise and document ablation results and significantly reduce fluoroscopy time, they fail to display the complexity of atrial activation during AF. This is mainly due to a limited number of simultaneously recorded electrograms and the low spatial resolution which is sufficient for its clinical use. At present, high-resolution mapping of AF in patients is only feasible during cardiac surgery. Endocardial catheter- based systems that have recently become available have to be further evaluated but might provide an option in this setting in the near future.