Total Quality Management (TQM) is a methodology that focuses on customer satisfaction and views quality as a strategic issue. The key principles of TQM include making quality everyone's responsibility, continuous quality improvement, cooperation between employees and management, and training. The Plan-Do-Check-Act cycle is used for continuous process improvement by planning a change, implementing it, checking the results, and acting on the findings. Tools of TQM include check sheets, cause-and-effect diagrams, Pareto charts, flowcharts, histograms, and brainstorming to identify and address quality issues.