The Python standard REPL (Read-Eval-Print Loop) lets you run code interactively, test ideas, and get instant feedback. You start it by running the python command, which opens an interactive shell included in every Python installation.
In this tutorial, you’ll learn how to use the Python REPL to execute code, edit and navigate code history, introspect objects, and customize the REPL for a smoother coding workflow.
By the end of this tutorial, you’ll understand that:
- You can enter and run simple or compound statements in a REPL session.
- The implicit
_variable stores the result of the last evaluated expression and can be reused in later expressions. - You can reload modules dynamically with
importlib.reload()to test updates without restarting the REPL. - The modern Python REPL supports auto-indentation, history navigation, syntax highlighting, quick commands, and autocompletion, which improves your user experience.
- You can customize the REPL with a startup file, color themes, and third-party libraries like Rich for a better experience.
With these skills, you can move beyond just running short code snippets and start using the Python REPL as a flexible environment for testing, debugging, and exploring new ideas.
Get Your Code: Click here to download the free sample code that you’ll use to explore the capabilities of Python’s standard REPL.
Take the Quiz: Test your knowledge with our interactive “The Python Standard REPL: Try Out Code and Ideas Quickly” quiz. You’ll receive a score upon completion to help you track your learning progress:
Interactive Quiz
The Python Standard REPL: Try Out Code and Ideas QuicklyTest your understanding of the Python standard REPL, which lets you run code interactively to try out ideas, explore libraries, and debug code.
Getting to Know the Python Standard REPL
In computer programming, you’ll find two kinds of programming languages: compiled and interpreted languages. Compiled languages like C and C++ have an associated compiler program that converts the language’s code into machine code.
This machine code is typically saved in an executable file. Once you have an executable, you can run your program on any compatible computer system without needing the compiler or the source code.
In contrast, interpreted languages like Python need an interpreter program. This means that you need to have a Python interpreter installed on your computer to run Python code. Some may consider this characteristic a drawback because it can make your code distribution process much more difficult.
However, in Python, having an interpreter offers one significant advantage that comes in handy during your development and testing process. The Python interpreter allows for what’s known as an interactive Read-Eval-Print Loop (REPL), or shell, which reads a piece of code, evaluates it, and then prints the result to the console in a loop.
The Python REPL is a built-in interactive coding playground that you can start by typing python in your terminal. Once in a REPL session, you can run Python code:
>>> "Python!" * 3
Python!Python!Python!
>>> 40 + 2
42
In the REPL, you can use Python as a calculator, but also try any Python code you can think of, and much more! Jump to starting and terminating REPL interactive sessions if you want to get your hands dirty right away, or keep reading to gather more background context first.
Note: In this tutorial, you’ll learn about the CPython standard REPL, which is available in all the installers of this Python distribution. If you don’t have CPython yet, then check out How to Install Python on Your System: A Guide for detailed instructions.
The standard REPL has changed significantly since Python 3.13 was released. Several limitations from earlier versions have been lifted. Throughout this tutorial, version differences are indicated when appropriate.
To dive deeper into the new REPL features, check out these resources:
The Python interpreter can execute Python code in two modes:
- Script, or program
- Interactive, or REPL
In script mode, you use the interpreter to run a source file—typically a .py file—as an executable program. In this case, Python loads the file’s content and runs the code line by line, following the script or program’s execution flow.
Alternatively, interactive mode is when you launch the interpreter using the python command and use it as a platform to run code that you type in directly.
In this tutorial, you’ll learn how to use the Python standard REPL to run code interactively, which allows you to try ideas and test concepts when using and learning Python. Are you ready to take a closer look at the Python REPL? Keep reading!
What Is Python’s Interactive Shell or REPL?
When you run the Python interpreter in interactive mode, you open an interactive shell, also known as an interactive session. In this shell, your keyboard is the input source, and your screen is the output destination.
Note: In this tutorial, the terms interactive shell, interactive session, interpreter session, and REPL session are used interchangeably.
Here’s how the REPL works: it takes input consisting of Python code, which the interpreter parses and evaluates. Next, the interpreter displays the result on your screen, and the process starts again as a loop.
So, Python’s REPL is an interactive way to talk to your computer using the Python language. It’s like a live chat. The whole process is known as a REPL because it goes through four steps that run under the hood:
- Reading your input, which consists of Python code as expressions and statements
- Evaluating your Python code, which generates a result or causes side effects
- Printing any output so that you can check your code’s results and get immediate feedback
- Looping back to step one to continue the interaction
This feature of Python is a powerful tool that you’ll wind up needing in your Python coding adventure, especially when you’re learning the language or when you’re in the early stages of a development process. That’s because the REPL offers several benefits, which you’ll learn about next.
Why Use a Python REPL?
As a Python programmer, you may spend considerable time in interactive mode. This mode provides a quick way to try out ideas and code snippets. In a REPL session, you can do some or all of the following tasks:
- Explore and learn Python syntax
- Try out and prove ideas, concepts, and implementations
- Quickly evaluate if your code snippets work
- Dive into the language behaviors
- Edit and refactor your code for later use in script mode
- Perform code and type introspection
- Get interactive help on how to use the language
- Debug code snippets
- Explore standard-library and third-party modules, libraries, and APIs
- Inspect the implementation of classes, functions, and other objects
Clearly, as a Python developer, you’ll have many reasons to spend a lot of time in REPL sessions, working interactively with the interpreter. The most relevant benefit of using a REPL session is getting immediate feedback on how your code works.
Interactive mode is one of the best features of Python. It allows you to test solutions and experiment with the language in real time. If you want to know how something works, then just try it in an interactive shell.
You should definitely consider the interactive shell a powerful learning tool, especially if your previous programming experience has been with compiled languages that don’t provide a REPL.
While learning Python or exploring new features and concepts, you’ll notice that many examples in the Python documentation, online tutorials, manuals, and courses are copied and pasted from an interactive session. You’ll recognize them because of the REPL’s characteristic prompts, which you’ll get to know in the Running the python Command section.
With this introduction to interpreters and REPLs, you’re ready to get into action. In the following section, you’ll learn how to start and terminate a Python interactive session.
Starting and Terminating REPL Interactive Sessions
The Python standard REPL is available in every Python installation. To start a new REPL or interactive session, you just need to run the Python interpreter in interactive mode from your command line. This mode will present you with a shell environment where you can introduce and execute Python code.
In the following sections, you’ll learn how to start a new Python interactive shell using the python command and some of its command-line options.
You’ll also learn about the standard look and feel of a Python interactive shell, along with some of its core characteristics and features. Finally, you’ll learn how to terminate a Python interactive session.
Running the python Command
Once you’ve installed Python on your computer, you can immediately begin using the REPL. To start a Python interactive session, open a command-line window and run the python command without arguments:
$ python
This command makes Python enter its interactive mode. The interpreter will run, and you’ll get an output that looks something like this:
Python 3.14.0 (main, Oct 11 2025, 20:47:48) ... on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
The first line of this output shows information about your current Python version and the platform on which you’re running the interpreter. The second line shows a message with commands that you can run to get additional information about Python in general.
The last line, which is highlighted in the output, shows the primary prompt of the standard Python REPL. By default, this prompt consists of three greater-than signs (>>>), also known as chevrons. Its purpose is to communicate that the interpreter is ready to accept input.
Note: The Python standard REPL before Python 3.14 doesn’t support syntax highlighting.
The interpreter also has a secondary prompt represented by three dots (...). This prompt appears when you’re entering compound statements or line continuations. You’ll learn more about this prompt in the Running Compound Statements and Dealing With Explicit and Implicit Line Continuations sections.
Passing Command-Line Options to the python Command
The python command can take several command-line options. Some of these can be especially useful when working in a REPL session. One of the most relevant options in this context is the -i flag. This option causes the interpreter to enter interactive mode after running a script or executing a piece of code using the -c option.
Note: The -c command-line option allows you to quickly run a Python statement or expression that you provide as a string on your command line. Try out the command python -c 'print("Hello, World!")' to see this option in action.
You can use the -i option to check the current global variables in your script or to inspect the stack trace when your program raises an exception.
To try this option out, say that you have the following sample script:
sample.py
def read_data():
# Read data from a file or database...
return [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
sample = read_data()
def mean(data):
return sum(data) / len(data)
average = mean(sample)