GAMS is a high-level modeling system for mathematical programming and optimization. Designed for complex, large-scale modeling applications, GAMS provides: algebraic model representation, separation of model and data, support for various problem types (LP, NLP, MIP, MINLP), and interfaces to numerous solvers. Features include: conditional statements and loops, dollar control options, model libraries (GAMSlib with hundreds of examples), and comprehensive documentation. GAMS syntax emphasizes sets and indexed operations, making it powerful for multi-dimensional problems. The IDE includes debugging tools, solution analysis, and visualization. Used extensively in energy systems modeling, economic equilibrium models, supply chain optimization, and policy analysis.