Simulation-based training (SBT) is becoming widely used in medical education to help residents and medical students develop good technical skills before they practice on real patients. SBT seems ideal because it provides a nonthreatening controlled environment for practice with immediate feedback and can include objective performance assessment. However, various forms of SBT and assessment often are being used with limited evidence-based data to support their validity and reliability. In addition, although SBT with high-tech simulators is more sophisticated and attractive, this is not necessarily superior to SBT with low-tech (and lower cost) simulators. Therefore, understanding the types of surgical simulators and appropriate applications can help to ensure that this teaching and assessment modality is applied most effectively. This article summarizes the key concepts that are needed to use surgical simulators effectively for teaching and assessment.