A walled garden in marketing refers to a closed digital ecosystem where a company controls user data and restricts external access. Major advertising platforms like Google, Facebook, and Amazon operate as walled gardens, limiting third-party tracking and requiring advertisers to rely on their proprietary data. This poses challenges for CRM users seeking cross-platform customer insights. Businesses must adapt by leveraging first-party data, improving CRM segmentation, and using AI-driven audience analysis. As data privacy regulations increase, CRM strategies must focus on ethical data collection and customer trust to navigate walled garden limitations effectively.