Walled gardens in cybersecurity refer to closed digital ecosystems where a single company exerts significant control over user access, data, and the advertising inventory within its platform. Unlike the open internet, these environments restrict interoperability and limit the flow of information to what the controlling entity permits. This control can enhance security and privacy for users but also raises concerns about transparency, data ownership, and competition. Major technology companies, such as Google, Facebook, and Apple, often operate walled gardens to manage user experience, protect proprietary data, and maximize revenue from advertisements. For cybersecurity professionals, understanding walled gardens is crucial for navigating data privacy, compliance, and secure integrations.