What is the primary purpose of a 'Project' in Claude.ai?

A Project keeps one body of work — its chats, its uploaded files and its custom instructions — together in a single, persistent workspace. That is the purpose: continuity. A standalone conversation starts from nothing every time, so the background you spent ten minutes explaining yesterday has to be explained again today, and pasting the same specification into chat after chat is both slow and a place for versions to drift apart.

Inside a Project, the knowledge you add lives at the Project level rather than inside one conversation. Every chat you start there can draw on it, and the custom instructions you set apply to all of them, so Claude holds the same context and the same standing brief across the whole effort. That is what makes a Project the right container for ongoing work — a codebase, a research thread, a document you keep returning to — and an ordinary chat the right one for a single question you will not revisit.