Claude Projects enables organizations to create purpose-built AI assistants with persistent memory and custom knowledge. Setup workflow: 1) Create project with clear name and description, 2) Add project instructions defining role, tone, constraints ("You are our technical writing assistant, expert in our product. Always reference our style guide. Never speculate about features not in the provided docs."). 3) Upload relevant documents - product documentation, style guides, customer personas, code repositories. Projects remember conversation context and uploaded files persistently. Team use cases: Documentation assistant - upload all internal docs, engineers ask natural language questions and get answers with citations. Marketing content creator - upload brand guidelines, target personas, past campaigns; generates on-brand content quickly. Customer success - upload all customer data, tickets, and FAQs; support agents get suggested responses. Engineering - upload codebase context, architecture docs; new team members onboard faster. Best practices: keep instructions focused and specific (under 2000 tokens), refresh knowledge base monthly with updated docs, create separate projects for different teams/purposes.