This document discusses key aspects of maintenance engineering including productivity, quality, reliability, and maintainability (PQRM). It explains that the right maintenance policy is required to avoid over or under maintenance. Good maintenance practices can increase equipment lifespan. PQRM are important for industry profitability. Productivity measures economic efficiency and output. Quality ensures products and processes meet standards. Reliability focuses on consistent performance over time. Maintainability refers to the ease of maintaining equipment. Quality circles in maintenance help solve work-related problems.