Program Evaluation and Review Technique (PERT) charts, also known as PHRT charts, are used to manage and schedule complex projects. They help in planning and tracking project activities, estimating time, identifying critical paths, and managing resources. PERT charts are particularly useful for projects with uncertain or variable durations, where activities may overlap or depend on each other. By visualizing the project network and critical paths, project managers can make informed decisions and allocate resources effectively1.