Contributed to the techeer-sv/2024-Team-Joe-backend-study repository by developing structured documentation for Effective Java Chapter 7, focusing on lambdas and streams. The work involved authoring learning materials in Markdown, centralizing resources to support onboarding and knowledge transfer within the backend study group. Repository hygiene was improved by identifying and removing a duplicate filename in the SangJin directory, which enhanced maintainability and reduced confusion for contributors. All changes were implemented through targeted commits, emphasizing careful file management and clear naming conventions. The approach demonstrated attention to documentation quality and repository organization, aligning with the team’s collaborative learning objectives.