Question: During installation process (Windows OS) I have 2 options:  Add Miniconda to my PATH environment variable Register Miniconda as my default Python  The first option is pretty obvious. I understand it completely. But what about the second? What is meant by the word "register"? It creates the file with the string "Ok I have registered your Python"or what? What specific operations will be performed? It's so confusing. I have read the whole documentation on their site, but I couldn't find anything about this.

Answer: I've investigated this issue today and revealed the secret within. You mean the following Anaconda installer UI, right?  I give my conclusion first. What he says is:  Register Anaconda3 as my default Python 3.9  NOT  Register Anaconda3 as my default Python  That means,  he can NOT determine what Python version, 3.5, 3.8 or 3.9, becomes your default version. He can only determine that: If the Python Launcher(py.exe), at one run, determines that 3.9 should be used, py.exe should choose Anaconda's Python 3.9 instance.  I verify my conclusion using Anaconda3-2022.05-Windows-x86_64.exe using a series of experiments. EXP.0 : Preparation Write a t3.py with content: #!/usr/bin/python3 import sys print(sys.executable)  This, when run, will show us which python.exe is being used. Install python.org official(just call it 'official' for brevity) python-3.5.4.exe, with default options. We'll get a regkey  [HKCU\SOFTWARE\Python\ PythonCore \3.5-32]  and python.exe location is registered there.  According to PEP-514, PythonCore is the "company name" chosen by python.org for itself. Now, run t3.py, we see that this very Python 3.5 is used.  EXP.1 : Add Anaconda over official 3.5 Now, install Anaconda, ticking the "Register 3.9" option, I install it to d:\Anaconda3. Then we see two regkeys are created. First, [HKCU\SOFTWARE\Python\ContinuumAnalytics\Anaconda39-64], this marks Anaconda's own Python instance. Second, [HKCU\SOFTWARE\Python\PythonCore\3.9], this pretends that an official Python instance is installed. Due to this, t3.py now says d:\anaconda3\python.exe is used.    Yes, If we didn't tick the "Register 3.9" option, the [HKCU\SOFTWARE\Python\PythonCore\3.9] regkey will not be created, so Anaconda will not be chosen by py.exe .  EXP.2 : Add Anaconda over official 3.5 & 3.10 Now go back to EXP.0 state -- I personally use a VM and revert to EXP.0 snapshot. We install an official python 3.10 , followed by installing Anaconda, still ticking "Register 3.9" option. Then what will happen to t3.py? The answer is,  C:\Users\chj\AppData\Local\Programs\Python\ Python310 \python.exe  Checking the registry again, the 3.9 (marked as orange) node is still created by Anaconda installer, but it is not picked by py.exe as the default version. Apparently, py.exe picks the latest version number.  EXP.3 : Anaconda installer BUG Things are not over. If we already have official Python 3.9, and we got further install Anaconda(providing his own 3.9), then what happens? Anaconda will first kindly prompt us he will overwrite the 3.9 pointer, which looks quite reasonable according to EXP.1 and EXP.2 .  However, after installing, t3.py shows the default 3.9 still points to the official one, Anaconda's overwriting does NOT take place. Hmm, apparently, that's BUGGY.