Threat modeling is a systematic process for identifying, analyzing, and prioritizing security threats in systems. Advanced threat modeling goes beyond basic frameworks: it handles complex architectures (microservices, cloud), emerging threats (supply chain attacks, API security), and zero-trust security models. Advanced approaches include data flow diagrams (DFD), attack trees, STRIDE methodology, and integration with secure development lifecycles. The goal is to build security into systems from design, not after-the-fact.