Every running program on a Linux system is a process — an instance of an executable with its own memory space, file descriptors, and process ID (PID). Bresnahan and Blum explain the process lifecycle from creation (fork/exec) through execution to termination, and the tools for monitoring, controlling, and prioritizing processes. Understanding process management is essential for diagnosing performance problems, managing server workloads, and ensuring critical services stay running. A process is not the same as a program: a single program can spawn multiple processes, and understanding this distinction is key to managing Linux systems effectively.