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Hey, in this video, we will talk about Python versions.

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You will understand what a Python version is and why it is important to know about Python versions.

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So let's begin let's talk about some history first, Python version 1.0.0 or simply Python one was released

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in 1994 and six years after that, Python two was released.

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In 2000.

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Eight years later, point three was released and currently Python three is the current version now.

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These were major releases, 1 to 3, but there are also minor releases and patch releases as well,

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which I'll talk about now.

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So when you download a python interpreter from Python dot org, you download something like Python 3.8

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11.2 or python three point 12.7 or python three point 10.8 etc..

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Now the last number.

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Is the patch release.

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So this is a release of a new Python version.

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For example, when we switch from three point 11.1 to 3.11 point two.

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So the Python developer team releases Python three point 11.2.

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And in that release, what happens is that there are bug fixes and other small changes in that particular

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release.

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Now this release is backwards compatible, which I'll talk about in just a bit.

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Then we have the minor releases.

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Now these are bigger features.

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So it's about, for example, switching from Python 3.10 to Python 3.11.

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So the second number indicates bigger features in the newer version that is released.

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And this is also backward compatible.

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Now, when we have a major release, for example, when we when we go from Python two to Python three.

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There are many big features that were released and the code is not backwards compatible.

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Now, what does backwards compatible mean?

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This is what I'll explain right now.

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So let's look at an example for that.

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Here.

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And this winter here I've started a Python 2.7 interactive shell, so I'm using the interpreter of Python

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2.7, which was released many years ago.

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And down here I've started a Python 3.10.

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Interactive shell.

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So I'm using the Python 3.10 interpreter down here now in Python 2.7 to print a string we could use

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print.

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Hello.

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Just like you see, it's here without the parentheses and you get the hello string.

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Ah, but in Python 3.10 if you do print hello like that, you'll get an error.

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So that means python 3.10.

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Or to be more exact, Python three is not backwards compatible because what's exactly a release?

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A release, For example, when Python three was released, what happens is that two things.

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First is that an interpreter program is created and you can download that, but also the documentation

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of the language changes to fit this new interpreter.

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So the new interpreter expects this kind of code print with parentheses.

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So like that.

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So the new interpreter for Python three expects that.

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Code and in the documentation you'll also see this code documented.

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And so this new version of Python Python three ignores the code that was available in Python two.

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Now, practically for programmers, what does it mean practically?

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Well, let's suppose that you have written a web application and the code is something like this.

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Let's suppose this is a code.

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So you have written it in Python two.

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And this code is now running on a server computer.

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And this code produces your website, your web application.

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But now Python three is released.

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So you have two choices.

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Either you ignore Python three and you keep running this code using your Python 2.7 interpreter or 2.6

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or whatever.

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So python two and your app will keep running just fine.

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Right?

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So you can ignore python three.

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Or the other option is that you go to your code and you make the necessary changes.

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So you add parentheses here in this Hello string and here row inputs you change it to input because

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in Python three row input is not used anymore, so input is used instead.

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And so once you make this changes, then in the server you instruct your server to run your code using

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part from three The Python three interpreter.

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In that case, you can say that you have upgraded from Python two to Python three.

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So after doing these two things, changing the code to fit Python three syntax and also changing the

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Python interpreter to to run this code using the Python three interpreter.

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Now, this could be a hustle.

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So many programmers could just leave the code base to run on Python two and they don't change the code.

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But after many years, Python two will not be supported anymore.

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So there might be security issues with Python two.

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And in that case, as a developer, you have to go to your code base and change the code base to Python

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three.

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So that you benefit from this minor releases of Python like the minor release here and the patch, which

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will happen in the current major version of Python.

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But in the previous major version such as Python four one or two, these changes will stop.

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After some time.

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So the developers of the Python team will not be working any more on Python two.

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So that's what you should know about Python versions.

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Now, as a learner, it doesn't really matter if you're using Python 3.10 or Python 3.12.

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The changes are very, very small.

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And so the code you wrote using Python 3.10 in mind will work even if you run it with Python 3.12 for

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later on because you are still in the same major version.

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Only if Python four is released later on, then you might want to think about upgrading your code to

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Python four.

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As I explained when I did the comparison between Python two and three.

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Yeah, that's.

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Thanks and see you later.