Rational Team Concert is a tool that allows development teams to plan projects, track work items and code changes, and collaborate in one integrated environment. It provides source control, work item tracking, build management, and dashboards. This helps teams work more efficiently through features like real-time planning, traceability between code and work items, continuous integration, and visibility into project status. The document discusses how Rational Team Concert supports agile project management practices like iteration planning, tracking progress through burndowns, and parallel development with source code management.