The document discusses the Improve phase of the Lean Six Sigma methodology. It provides an overview of the key tools and activities used in the Improve phase, including identifying and prioritizing root causes, developing and selecting solutions, implementing pilots, and developing implementation plans. It also discusses tollgate reviews, which are checkpoints to review progress. The Improve phase aims to develop, test, and select solutions to address the root causes identified in the Analyze phase in order to meet the project goals.