This document discusses SAP Project System (PS) and its key components and functions. It describes the project definition and work breakdown structure (WBS) elements that define tasks and activities. It outlines the phases of projects including planning, defining activities, allocating resources, budgeting, and reporting. It also discusses how PS integrates with other SAP modules like Sales and Distribution (SD), Materials Management (MM), and Financial Accounting (FI) for functions like ordering, purchasing, billing, and settlement.