Installing Python

To get started working with Python 3, you’ll need to have access to the Python interpreter. There are several common ways to accomplish this:

Python can be obtained from the Python Software Foundation website at python.org. Typically, that involves downloading the appropriate installer for your operating system and running it on your machine.
Some operating systems, notably Linux, provide a package manager that can be run to install Python.
On macOS, the best way to install Python 3 involves installing a package manager called Homebrew. You’ll see how to do this in the relevant section in the tutorial.
On mobile operating systems like Android and iOS, you can install apps that provide a Python programming environment. This can be a great way to practice your coding skills on the go.

Alternatively, there are several websites that allow you to access a Python interpreter online without installing anything on your computer at all.

Note: There is a chance that Python may have been shipped with your operating system and is already installed. Even if that is the case, it may be that the installed version is outdated, in which case you will want to obtain the latest version anyhow.

In this Python installation guide, you’ll see step by step how to set up a working Python 3 distribution on Windows, macOS, Linux, iOS, and Android. So let’s get started!

Windows

It is highly unlikely that your Windows system shipped with Python already installed. Windows systems typically do not. Fortunately, installing does not involve much more than downloading the Python installer from the python.org website and running it. Let’s take a look at how to install Python 3 on Windows:

Step 1: Download the Python 3 Installer

Open a browser window and navigate to the Download page for Windows at python.org.
Underneath the heading at the top that says Python Releases for Windows, click on the link for the Latest Python 3 Release - Python 3.x.x. (As of this writing, the latest is Python 3.6.5.)
Scroll to the bottom and select either Windows x86-64 executable installer for 64-bit or Windows x86 executable installer for 32-bit. (See below.)

Sidebar: 32-bit or 64-bit Python?
For Windows, you can choose either the 32-bit or 64-bit installer. Here’s what the difference between the two comes down to:
If your system has a 32-bit processor, then you should choose the 32-bit installer.
On a 64-bit system, either installer will actually work for most purposes. The 32-bit version will generally use less memory, but the 64-bit version performs better for applications with intensive computation.
If you’re unsure which version to pick, go with the 64-bit version.
Note: Remember that if you get this choice “wrong” and would like to switch to another version of Python, you can just uninstall Python and then re-install it by downloading another installer from python.org.

Step 2: Run the Installer

Once you have chosen and downloaded an installer, simply run it by double-clicking on the downloaded file. A dialog should appear.

Important: You want to be sure to check the box that says Add Python 3.x to PATH as shown to ensure that the interpreter will be placed in your execution path.

Then just click Install Now. That should be all there is to it. A few minutes later you should have a working Python 3 installation on your system.

Mac

While current versions of macOS (previously known as “Mac OS X”) include a version of Python 2, it is likely out of date by a few months. Also, this tutorial series uses Python 3, so let’s get you upgraded to that.

The best way we found to install Python 3 on macOS is through the Homebrew package manager. This approach is also recommended by community guides like The Hitchhiker’s Guide to Python.

Step 1: Install Homebrew (Part 1)

To get started, you first want to install Homebrew:

Open a browser and navigate to http://brew.sh/. After the page has finished loading, select the Homebrew bootstrap code under “Install Homebrew”. Then hit Cmd+C to copy it to the clipboard. Make sure you’ve captured the text of the complete command because otherwise the installation will fail.
Now you need to open a Terminal.app window, paste the Homebrew bootstrap code, and then hit Enter. This will begin the Homebrew installation.
If you’re doing this on a fresh install of macOS, you may get a pop up alert asking you to install Apple’s “command line developer tools”. You’ll need those to continue with the installation, so please confirm the dialog box by clicking on “Install”.

At this point, you’re likely waiting for the command line developer tools to finish installing, and that’s going to take a few minutes. Time to grab a coffee or tea!

Step 2: Install Homebrew (Part 2)

You can continue installing Homebrew and then Python after the command line developer tools installation is complete:

Confirm the “The software was installed” dialog from the developer tools installer.
Back in the terminal, hit Enter to continue with the Homebrew installation.
Homebrew asks you to enter your password so it can finalize the installation. Enter your user account password and hit Enter to continue.
Depending on your internet connection, Homebrew will take a few minutes to download its required files. Once the installation is complete, you’ll end up back at the command prompt in your terminal window.

Whew! Now that the Homebrew package manager is set up, let’s continue on with installing Python 3 on your system.

Step 3: Install Python

Once Homebrew has finished installing, return to your terminal and run the following command:

Shell

$ brew install python3

Note: When you copy this command, be sure you don’t include the $ character at the beginning. That’s just an indicator that this is a console command.

This will download and install the latest version of Python. After the Homebrew brew install command finishes, Python 3 should be installed on your system.

You can make sure everything went correctly by testing if Python can be accessed from the terminal:

Open the terminal by launching Terminal.app.
Type pip3 and hit Enter.
You should see the help text from Python’s “Pip” package manager. If you get an error message running pip3, go through the Python install steps again to make sure you have a working Python installation.

Assuming everything went well and you saw the output from Pip in your command prompt window…congratulations! You just installed Python on your system, and you’re all set to continue with the next section in this tutorial.

[Reference: https://realpython.com/installing-python/]