This lecture covers the process state transition diagram, detailing the various states a process can occupy during its lifecycle, including running, ready, and blocked. The instructor explains how processes transition between these states based on system calls and events, such as I/O operations. The lecture also introduces the operating system's mechanisms for managing processes, including the process control block and the tree structure of processes. Key system calls like fork(), exec(), wait(), and exit() are discussed, illustrating how they facilitate process creation, execution, and termination. The instructor emphasizes the importance of these calls in managing process states and ensuring efficient CPU utilization. Additionally, the lecture highlights the implications of blocking states and the role of the operating system in scheduling processes. By the end of the lecture, students gain a comprehensive understanding of process management and the significance of the process state transition diagram in operating systems.