The "bird cage" prompt is a mental framework used by a ChatGPT power user to keep individual conversations focused and prevent work, personal, and creative ideas from mixing. The prompt instructs ChatGPT to imagine each project lives inside its own bird cage, entering the "[Project Name] cage" and using only information belonging to that project, not mixing in ideas from other projects unless specifically asked, and stopping to ask if the user wants to switch cages if something from another cage is mentioned. It is not an official OpenAI prompt or an alternative to ChatGPT Projects, but can be used inside a Project or in a regular chat. The user employs it for queries that start small or for tasks within an existing Project that need dedicated focus, and it is also a good option for free tier users when ChatGPT Projects isn't available. The prompt works by countering ChatGPT's ability to maintain context, which is usually helpful but can allow unwanted ideas, such as from a grocery list or vacation planning, to sneak into an article-writing conversation.