When you opened this blog in Chrome (or any other browser) on your computer, what was going on in the background?
If you open Task Manager or Activity Monitor right now, you’ll likely see multiple entries for chrome.exe or Google Chrome, each one representing a separate process. Within each of these processes, multiple threads are working together to handle things like tabs, extensions, and background tasks.
This type of activity occurs continuously throughout your device, not only in your browser but also in all of the apps you use. It is powered by a structure of programs, processes, and threads working together to keep things running smoothly. However, what exactly are these terms? How does your computer handle them? And why is it important if something operates as a thread or a process?
If this sounds a bit confusing, don’t worry. We’ll walk you through the difference between process and thread in a simple way, with visual hierarchy and analogies that make it easy to understand.
Table of Contents
What is a Program?
Before we get into threads and processes, let us take a step back and look at how everything begins inside a computer, starting with the program that the CPU needs to work with.
A program is a file that holds a set of instructions your computer can follow.
It could be anything from a web browser to a calculator. When you install software on your computer, what you’re doing is saving a program; a file written in a programming language, stored as something like chrome.exe, calculator.app, or notepad.py.
At this point, the program is just sitting on your system. It is not using memory or processing power. Nothing is running yet. It is like a music track sitting in your playlist. Until you hit play, it does not make a sound.
The same goes for a program. It needs to be opened by the system and loaded into memory before anything starts. That is when it becomes active.
This is how a program sits in memory before it runs. The text section holds the actual code to be executed by the CPU, while the data section stores constants, variables, and other fixed values the program needs.
How Does Code Turn into a Process?
Every program starts as code. You write it in a programming language like Python, Java, or C. At this point, it is simply a list of instructions sitting in a file.
But here’s the catch. Your computer does not understand Python. Or Java. Or any human-written code for that matter. It only understands binary: long sequences of ones and zeroes that represent signals to the CPU.
To bridge this gap, the code needs to be translated. This is done in one of two ways: compiling or interpreting.
In both cases, the end goal is the same. The code you wrote gets turned into machine instructions. Ones and zeroes. Signals the CPU can act on.
Once that translation is done, the operating system steps in. It loads the program into memory and prepares the CPU to start running it.
At this point, your program is no longer just sitting still. It is about to become a process, and that is where the real work begins.
Compiled languages like C, C++ are translated into binary before they run. This makes them fast and efficient, since the CPU can execute the code directly. But they are less flexible. Once compiled, making changes takes time, and the program may not work across different systems without rebuilding.
Interpreted languages like Python, JavaScript, and Ruby are translated on the fly while the program runs. This makes them easier to test, update, and move across platforms. However, they usually run slower because translation happens in real time.
In the end, both types of programs are turned into binary instructions.
What is a Process?
A process is what your program turns into when it starts running.
It is no longer just a file sitting quietly on your disk. Once loaded into memory and given resources by the operating system, it becomes something that actively does work: loading content, managing inputs, opening files, or responding to you in real time.
This is where your program comes alive.
How a Process Works?
Each process has its own memory space and system resources. It runs separately from everything else on your system. That means one process cannot interfere with another. So even if your browser crashes, your editor or music player keeps running, because each is a separate process.
The operating system handles everything, where the process lives in memory, what it is doing, which files it has open, and when it gets access to the CPU. Each process also has a unique process ID, environment settings, and priority level.
A process is made up of several memory regions and CPU-managed components:
- Code section: Contains the machine instructions that the CPU will execute.
- Data section: Stores global variables and constants used by the program.
- Stack: Manages function calls, parameters, and local variables.
- Heap: Handles dynamic memory created during execution.
- Registers: High-speed memory slots inside the CPU used to temporarily hold data and addresses during processing.
- Program counter: Keeps track of which instruction is currently being executed.
A running process includes memory sections and system-level details managed by the operating system.
Even on systems with a single CPU core, multiple processes can appear to run at the same time. That is because of context switching — the OS quickly switches between them, giving the impression of parallel execution.
Every time you open a new app, tab, or tool, you are creating a new process. From the OS’s perspective, that process is now something to manage, isolate, and schedule.
A real-time view from Task Manager: 216 processes and 2647 threads running in parallel, all managed by the OS behind the scenes.
A real-time view from Task Manager: 216 processes and 2647 threads running in parallel, all managed by the OS behind the scenes.
What is a Thread?
You are aware by now that a process is an active program. However, a process frequently has to manage multiple tasks simultaneously. Threads can help with that.
A thread is the smallest (and lightweight) unit of execution within a process. It shares memory space with other threads in the same process and executes a portion of the program. Compared to spinning up a completely new process, this makes it faster to start and switch between.
Some programs manage everything from the beginning to the end in a single thread. We refer to this as single-threaded. Others, such as loading images while reacting to user input, divide work among several threads. These programs, which use multiple threads, are typically more efficient.
Take your browser as an example. When you opened this blog:
- One thread handled the user input
- One displayed the layout
- Another fetched the images in the background
Within a single process, these threads collaborate while maintaining their independence and shared memory. Each knows what to do and when because it has its program counter and stack.
Difference between Single-Threaded and Multithreaded Processes
Difference between Single-Threaded and Multithreaded Processes
Threads Share Resources and Work Together
Since threads live within the same process, they share memory like the code section and heap. This makes them efficient. However, it is also implied that if they are not appropriately managed, they may interfere with one another. Unexpected behaviour may result from two threads attempting to update the same variable simultaneously. For this reason, when working with multiple threads, thread synchronisation and safety are crucial.
Most computers today have more than one CPU core (multi-core). The operating system is designed to take advantage of this. It can assign different threads to different cores, so they run at the same time.
This enables the responsiveness and fluidity of contemporary applications. One thread may be handling a video call, while another may be rendering a webpage or saving a file. By distributing the work, threads enable multitasking.
Programs can accomplish tasks more quickly, maintain a responsive interface, and optimise system resources by utilising multiple threads within a single process.
Concurrency vs Parallelism
On multicore systems, threads and processes can run at the same time. On single-core systems, the CPU quickly switches between tasks to create the illusion of simultaneous execution. The operating system handles this through a scheduler that divides CPU time across tasks.
Difference Between a Process and a Thread
At first sight, processes and threads might seem like similar building blocks. Both help your system do more than one thing at a time. But they work very differently under the hood.
A process is similar to a self-contained workspace. It has its memory, its own tools, and its own schedule. If something goes wrong inside a process, the damage usually stays contained. This makes processes more stable, but also heavier to create and slower to switch between. In that workspace, a thread is more akin to a team member. It is quick and effective because it uses the same resources and space as other threads running in the same process. However, a mistake in one thread can have an impact on all the others. That is why thread safety and coordination are so important.
Developers often balance control, safety, and speed when choosing between them. Better performance and responsiveness are made possible by threads, particularly on multicore computers where several threads can operate fully in parallel. But in order to prevent disputes, they also need to be carefully coordinated. On the other hand, processes have higher memory and CPU overhead but provide better fault isolation.
The majority of contemporary applications use a mix of both.
Consider the blog you’re reading in Google Chrome. Each tab runs as a separate process, which is why a crash in one tab does not affect the others. Within each process, multiple threads handle different tasks: user input, network requests, rendering, and smooth scrolling. If you open your Activity Monitor, you’ll notice several entries labeled “Google Chrome Helper (Renderer).”
These are distinct processes, each with their own memory allocation and thread count, as seen in the image below. Together, they coordinate in real time to deliver a seamless, multi-threaded browsing experience.
Process Vs Threads in OS
| Aspect | Process | Thread |
| Definition | Independent unit with its memory and resources | Lightweight unit within a process that shares memory |
| Creation Overhead | Higher needs its own memory allocation and control structures | Lower shares memory and resources with its parent process |
| Isolation | Completely isolated from other processes | Shares memory space with other threads in the same process |
| Resource Allocation | Has its own code, data, heap, stack, and registers | Owns a stack and program counter but shares heap and code |
| Independence | Runs independently. One process does not affect another | Dependent on the parent process. Can affect or be affected by siblings |
| Failure Impact | One process crashing does not affect others | A crashing thread may bring down the whole process |
| Communication | Requires inter-process communication (IPC), which is slower and more complex | Easier and faster via shared memory |
| Synchronization | Less synchronization needed | Requires synchronization to avoid data races and deadlocks |
| Use Cases | Running independent applications (e.g., Word, Excel, browser tabs) | Performing multiple tasks in one app (e.g., rendering, user input) |
| Memory Usage | More memory-intensive | More memory efficient |
| Scheduling | Handled separately by the OS scheduler | Handled as part of the parent process |
When Should a Developer Use a Thread or a Process?
Both threads and processes are crucial from the perspective of a system. But from the standpoint of a developer, picking the best one relies on the goals and structure of their application:
- Choose a new process when:
- You need isolation. Processes do not share memory space, so bugs, memory leaks, or crashes stay contained.
- You are handling multiple heavy or long-running tasks that should not interfere with each other.
- You are working with multi-user or multi-instance applications, where each instance should operate independently.
- You want security boundaries, like sandboxing untrusted components.
- Choose a new thread when:
- You need shared memory and want tasks to collaborate closely. Threads can easily access and modify the same data.
- You are optimizing for performance, especially on multicore CPUs. Threads allow you to break a task into parallel parts.
- You are working on responsive applications, like GUIs or real-time systems, where one thread handles the UI and others handle background work.
- You need lightweight concurrency, like downloading resources, parsing data, or listening to sockets, all in parallel.
Remember that although threads are lighter and spin up more quickly, synchronisation is more complicated. Mismanaged threads can lead to race conditions, deadlocks, and hard-to-reproduce bugs. Processes are heavier, but offer safety through isolation.
If you are curious about the difference between process and thread in Java, especially how threads work under the hood, this Java thread synchronization guide is a helpful next read.
Understanding the Difference Between Process and Thread Matters
Behind every app you build or use, processes and threads are quietly doing the work. They shape how software behaves, how fast it runs, and how safely it scales. As a developer, knowing how they operate is not just helpful, but essential. We hope this newly gained understanding will give you the confidence to design systems that are not only efficient but also stable and built to last.
Mastering the core concepts of processes and threads not only sharpens your system-level thinking but also makes debugging and performance tuning much easier, especially in real-world development. If you’re looking to strengthen these foundations while building full-fledged web applications, explore our Full Stack Web Developer MEAN Stack Certification Training. It’s a solid next step if you’re aiming to become a backend-ready, deployment-smart engineer.
Processes vs Threads – FAQs
1. What is the difference between a process and a thread?
A process is an independent unit of execution with its own memory space and system resources. A thread is a lightweight unit within a process that shares the same memory but runs its own code path. This makes threads faster to create and switch, while processes offer better isolation and safety.
2. Why are threads faster than processes?
Threads share the same memory space and resources within their parent process. This eliminates overhead like creating separate memory maps or duplicating resources. Context switching between threads is lighter and quicker, making multitasking more efficient.
3. When should I use a process instead of a thread?
Use a process when fault isolation is critical, such as running separate browser tabs or sandboxing untrusted code. Processes prevent failures from affecting each other since they operate in their own memory space.
4. How do threads and processes work on multicore CPUs?
On multicore systems, both threads and processes can run truly in parallel across CPU cores. This allows modern software to perform multiple tasks at once, such as handling user input, fetching data, and rendering graphics simultaneously.
5. What causes race conditions in multithreading?
Race conditions happen when multiple threads try to access and modify the same shared data at the same time without proper synchronization. To prevent this, developers use mechanisms like mutexes, semaphores, and critical sections to safely control access.