> ## Documentation Index > Fetch the complete documentation index at: https://docs.persistence.dev/llms.txt > Use this file to discover all available pages before exploring further. # Knowledge bases > Create reusable knowledge collections and attach them to agents. A knowledge base gives an agent information it can retrieve during a conversation. Use it for product information, policies, support material, or other content that should remain separate from the core prompt. Persistence Knowledge Base library showing ready, processing, and failed collections ## Create a knowledge base From the dashboard, open **Knowledge Base** and create a knowledge base with a clear name and description. Upload PDF files up to 5 MB each. Wait until processing finishes before attaching the knowledge base to a production agent. Open the agent's settings, select **Knowledge Base**, and add the ready knowledge base. Ask questions that should be answered, should combine nearby information, and should return a fallback because the answer is absent. ## Keep retrieval reliable Use **Retrieval Testing** to select a knowledge base, enter a representative query, adjust supported retrieval settings, and inspect the chunks the agent would receive. Persistence Knowledge Base retrieval testing screen * Keep each knowledge base focused on one domain. * Remove obsolete or conflicting documents. * Use descriptive headings and plain text in source documents. * Put behavior rules in the agent instructions, not only in the knowledge documents. * Re-test the agent after adding or deleting a document. An agent can only use a knowledge base that has finished processing. The agent settings identify knowledge bases that are not ready. Document processing moves through pending, extracting, chunking, embedding, and ready states. Replace a document when it reaches failed or upload failed. Knowledge base names can contain up to 128 characters and descriptions up to 512 characters. Deleting a knowledge base or a source document removes it from future retrieval. Review every agent that depends on that content before deleting it. Create, list, inspect, and delete knowledge bases through the public API.