Difference between python 2 and python 3

Being your first time of learning python can be so much confusing, just because you don't know of which version to learn. Truly, python 3 is the latest version of python but many programmers still use Python 2.7; As a beginner you need to know the difference between the two version before you learn.

Reasons for different version
The functionality of programming language is dynamic as new changes evolved. However,  the language need to be updated to meet up with developers demand. Python 3 was introduced in 2008 with the aim of making Python easier to use and change the way it handles strings to match the demands placed on the language today. Programmers who first learned to program in Python 2 sometimes find the new changes difficult to adjust to, but beginners often find it easy to use the latest python.
Python 3.0 is fundamentally different to previous Python releases because it is the first Python release that is not compatible with older versions. Programmers usually don’t need to worry about minor updates (e.g. from 2.6 to 2.7) as they usually only change the internal workings of Python and don’t require programmers to change their syntax. The change between Python 2.7 (the final version of Python 2) and Python 3.0 is much more significant — code that worked in Python 2.7 may need to be written in a different way to work in Python 3.0

 Difference between python 2 and python 3

• Print: In Python 2, “print” is treated as a statement rather than a function. There is no need to wrap the text you want to print in parentheses, although you can if you want. This can be confusing, as most other actions in Python use functions that require the arguments to be placed inside parentheses. It can also lead to unexpected outcomes if you put parentheses around a comma-separated list of items that you want to print. In contrast, Python 3 explicitly treats “print” as a function, which means you have to pass the items you need to print to the function in parentheses in the standard way, or you will get a syntax error. Some Python 2 programmers find this change annoying, but it can help to prevent mistakes.

• Integer Division: Python 2 treats numbers that you type without any digits after the decimal point as integers, which can lead to some unexpected results during division. For example, if you type the expression 3 / 2 in Python 2 code, the result of the evaluation will be 1, not 1.5 as you might expect. This is because Python 2 assumes that you want the result of your division to be an integer, so it rounds the calculation down to the nearest whole number. In order to get the result 1.5, you would have to write 3.0 / 2.0 to tell Python that you want it to return a float, that is, to include digits after the decimal point in the result. Python 3 evaluates 3 / 2 as 1.5 by default, which is more intuitive for new programmers.

• List Comprehension Loop Variables: In previous versions of Python, giving the variable that is iterated over in a list comprehension the same name as a global variable could lead to the value of the global variable being changed — something you usually don’t want. This irritating bug has been fixed in Python 3, so you can use a variable name you already used for the control variable in your list comprehension without worrying about it leaking out and messing with the values of the variables in the rest of your code.

• Unicode Strings: Python 3 stores strings as Unicode by default, whereas Python 2 requires you to mark a string with a “u” if you want to store it as Unicode. Unicode strings are more versatile than ASCII strings, which are the Python 2 default, as they can store letters from foreign languages as well as emoji and the standard Roman letters and numerals. You can still label your Unicode strings with a “u” if you want to make sure your Python 3 code is compatible with Python 2.

• Raising Exceptions: Python 3 requires different syntax for raising exceptions. If you want to output an error message to the user, you need to use the syntax:

raise IOError(“your error message”)
This syntax works in Python 2 as well. The following code works only in Python 2, not Python 3:
raise IOError, “your error message”
The two version is good. It depends on what you need to achieve with python.