This document provides a brief review of vision-based hand gesture recognition approaches. It discusses model-based approaches that use 3D hand models and appearance-based approaches that extract features directly from images without an explicit hand model. Model-based approaches attempt to match a 3D hand model to image data, while appearance-based approaches use classifiers on low-level features like color histograms or interest points. The document surveys recent works applying various features and machine learning methods for real-time hand gesture recognition.