Installing Python & pip

In the last chapter we made the case for Python. Now let's actually get it running on your computer - because everything that follows, every example and every chart, you'll want to run yourself. This is the one chapter that's mostly setup rather than ideas, so we'll keep it short, practical, and trap-free. Twenty minutes from now you'll have written and run your very first program.

Step 1: Get Python onto your computer

There are a few ways to install Python, but for an absolute beginner there's a clear winner: the official installer from python.org. It's free, it's maintained by the people who make Python, and it works the same on Windows and Mac.

Head to the downloads page and click the big button that says Download Python (it offers you the latest version automatically). Then run the file you downloaded.

On a Mac, the installer just walks you through Next - Next - Done. (macOS does ship with an ancient Python under the name python3, but installing the latest from python.org is cleaner and avoids surprises.)

Step 2: Check it actually worked

Installing software and confirming it installed are two different things. Let's confirm.

First, open a terminal - the plain text window where you type commands:

• Windows: press Start, type cmd, and open Command Prompt (or PowerShell).
• Mac: press Cmd+Space, type terminal, and open Terminal.

Now type this and press Enter:

python --version

You should see something like:

Python 3.14.4

The exact numbers will differ - any 3.x is perfect. If you see a version, congratulations: Python is installed and on your PATH.

Step 3: Your first program

Time for the rite of passage. Open a plain text editor, paste in the lines below, and save the file as hello.py. Then, in your terminal, run python hello.py.

# Your very first Python program.
# Save it as hello.py, then run it from a terminal with:  python hello.py
import sys

print("Hello, markets! Python is working.")
print("You are running Python version", sys.version.split()[0])

# Python is also a calculator. A quick profit check on one share:
buy_price = 100.0
sell_price = 105.5
profit = sell_price - buy_price
print(f"Bought at {buy_price}, sold at {sell_price}, profit of {profit} per share.")

Hello, markets! Python is working.
You are running Python version 3.14.4
Bought at 100.0, sold at 105.5, profit of 5.5 per share.

Three small ideas are hiding in there, and we'll spend whole chapters on each soon: print() shows text on screen, import borrows a ready-made tool (here sys, to read the version), and the last line does a little arithmetic and slots the answers into a sentence. Don't worry about the details yet - the point is simply that you ran code, and the computer answered.

Step 4: Meet pip, Python's gateway to half a million tools

Python by itself is powerful, but its real superpower is the enormous library of free add-on tools other people have written - including NumPy and pandas, which we'll use constantly. The program that fetches and installs those tools is called pip, and it came bundled with your Python install.

Check it's there:

pip --version

When the time comes, installing a library is gloriously simple - one line, like this (we'll do it for real in Chapter 19):

pip install pandas

That command reaches out to a giant online warehouse called PyPI - the Python Package Index - finds the tool, downloads it, and installs it for you.

Five common traps (and the one-line fix)

Almost every beginner hits one of these. Here's the cheat sheet so you don't lose an evening to it:

• "'python' is not recognized" (Windows) - PATH wasn't set. Re-run the installer and tick "Add python.exe to PATH".
• python opens version 2 or errors (Mac/Linux) - use python3 instead.
• pip not found - try pip3, or python -m pip which always works.
• You installed Python twice - stick to one version to avoid confusion; uninstall the spare.
• "Permission denied" when installing - don't fight it with admin rights; we'll use a clean virtual environment in Chapter 19, which sidesteps the whole problem.

Try it yourself

• Run python --version and note your version number. Anything starting with 3 is good to go.
• Change the sell_price in hello.py to a number below the buy price, save, and re-run. What does the profit line say now? (You just made Python report a loss.)
• Add one more line: print(2026 - 1991). Run it. You've just asked Python how old it is - we'll see why that number matters in a moment.

Recap

• Install Python from the official python.org installer - and on Windows, tick "Add python.exe to PATH".
• Confirm it with python --version in a terminal (use python3 if python doesn't behave).
• You wrote and ran your first program, hello.py - print, import, and a dash of arithmetic.
• pip installs free libraries from PyPI, a warehouse of over half a million tools - the engine behind Python's reputation.
• Setup traps are common and each has a one-line fix; pay the one-time tax and you're done.

You've got Python running and you've run code from a file. But typing into a bare terminal gets old fast. In the next chapter we'll set up a proper, friendly home for your code - VS Code - and meet Jupyter, the interactive notebook that traders love for poking at data.