A process is an active, executing instance of a program. When you launch an application or run a command, the operating system creates a process and allocates memory, file handles, and system resources to it. Each process runs in its own protected memory space, meaning one process cannot directly access or interfere with another's data without explicit permission.
Key characteristics of processes include:
- Process ID (PID): A unique identifier assigned by the operating system to track and manage each running process
- Memory isolation: Each process has its own virtual address space, protecting it from other processes
- Resource allocation: The OS assigns CPU time, RAM, and file descriptors to each process
- Independent lifecycle: Processes can start, pause, resume, and terminate independently
A single application may spawn multiple processes. For example, a web browser typically creates separate processes for tabs, extensions, and rendering engines. This isolation improves stability: if one process crashes, others continue running.
Processes differ from threads, which share memory within a single process and are lighter weight. A process can contain multiple threads, but processes themselves are heavier and more resource-intensive.
When troubleshooting slow computers or unresponsive applications, you can view active processes using Task Manager on Windows, Activity Monitor on macOS, or terminal tools like top or ps on Linux. This shows you which programmes are consuming CPU, memory, and other resources. Understanding processes helps you identify resource hogs, force-quit frozen applications, or diagnose why your system feels sluggish.