OpenProject is an open-source project management tool that allows for project planning, task management, timeline creation, and budget tracking. It can be used by distributed project teams for collaborative work. Key features include creating projects and assigning team members, adding work packages and milestones, generating Gantt charts to visualize timelines, defining and tracking budgets against actual costs, and logging work hours against tasks. The tool provides a comprehensive set of features to support project management from planning through execution.