Processes and Threads
When you launch an application, the operating system creates a process — a running instance of that program with its own memory and resources. Inside that process, threads handle different tasks simultaneously. Understanding this distinction helps explain why applications behave the way they do.
What Is a Process?
A process is a complete, independent program in execution. When you open a web browser, that's one process. Open a text editor, that's another. Each process gets its own isolated memory space, so one crashing program doesn't corrupt another's data.
Think of a process like a restaurant kitchen. It has its own space, equipment, and ingredients. What happens in one kitchen doesn't directly affect another restaurant down the street.
What Is a Thread?
A thread is a smaller sequence of execution inside a process. A single process can have multiple threads working on different tasks at the same time. They share the process's memory, which makes communication between them fast but also means they can interfere with each other.
In our kitchen analogy, threads are like individual cooks. Multiple cooks can prepare different dishes simultaneously — one handles appetizers while another works on the main course. They share the same kitchen space and ingredients, coordinating to get everything done faster.
Why Threads Matter
Modern applications use multiple threads to stay responsive. Consider a word processor:
- One thread handles what you type
- Another thread checks spelling in the background
- A third thread auto-saves your document
Without threads, the application would freeze every time it auto-saved. The user interface thread stays responsive while background threads handle other work.
When Things Go Wrong
Because threads share memory, problems in one thread can affect others. If a background thread crashes or gets stuck in an infinite loop, it might freeze the entire application. This is why a single frozen feature can make a whole program unresponsive.
Operating systems isolate processes from each other, so one crashed application doesn't bring down your whole computer. But threads within a process don't have that protection from each other.