Need of Variables
While programming, we very often need to access the memory to read and write data.
The memory addresses are hexadecimal values.
So, it is very hard to keep track of hexadecimal values while programming.
To manipulate memory address easily, we can attach a name to the memory address.
So, it will be very easy to make use of the memory address using a variable name rather than hexadecimal values.
Pictorial Explanation
In the above diagram, memory address 22fe4c has been mapped with the variable name letter.
Using variable letter, we can easily manipulate the memory address 22fe4c.
Similarly, using variable letter2, we can easily manipulate the memory address 22fe4d.
Variable Naming Rules in Python
1. Variable name should start with letter(a-zA-Z) or underscore (_).
Valid
age
_age
Age
Invalid
1age
2.In variable name, no special characters allowed other than underscore (_).
Valid
_age
age_
Invalid
age_*
+age
3.Variables are case sensitive.
age and Age are different, since variable names are case sensitive.
4.Variable name can have numbers but not at the beginning.
Example
Age1
Age2
5.Variable name should not be a Python keyword.Keywords are also called as reserved words.
Example
pass, break, continue.. etc are reserved for special meaning in Python. So, we should not declare keyword as a variable name.