We are transitioning from the programmatic to the cognitive computing era.IBM Deep Blue won against the world champion in Chess 1996. IBM Watson won against the two world champions in the famous US quiz show "Jeopardy" 2011. Since then, the press heavily established the term "Cognitive Computing" to the public. I will explain how IBM Watson works internally and start with Algebraic Text Extraction. DeepQA is the heart of IBM Watson and I will explain each component of this pipeline, the linguistic preprocessor, hypothesis generation, hypothesis and evidence scoring, final matching based on supervised learning and confidence estimation. Finally, I conclude with an overview of actual use cases and outline the roadmap of future work.