Atlassian Confluence is a wiki collaboration tool that allows teams to create rich content, collaborate on projects, and document knowledge. The document discusses how Confluence can be used for communication, collaboration, documentation, and as a knowledge repository. It provides examples of integrating Confluence with other tools like JIRA, Salesforce, and Box. The document concludes by recommending next steps for organizations to set up department spaces, a company glossary, and personal spaces to start utilizing Confluence.