A variable is a name that refers to a memory location. A Python variable, also known as an identifier, is used to store data. Python is not a “statically typed” language. We do not need to declare variables or their types before using them. When we first assign a value to a variable, it is created. A variable in Python is the name given to a memory location. It is the fundamental storage unit in a program.

There are some rules to assign a name to the variable.

Python variables creation rules:

• A variable name must begin with a letter or an underscore.
• A variable name must not begin with a number.
• Only alphanumeric characters and underscores (A-z, 0-9, and _) are permitted in variable names.
• The case of variable names matters.
• Reserved words (keywords) cannot be used to name variables.

Declaring Variable and Assigning Values:

Python does not require us to declare variables before using them in our code. It enables us to create a variable at the appropriate time.

In Python, we don’t need to declare variables explicitly. When we assign a value to a variable, it is automatically declared.

To assign a value to a variable, use the equal (=) operator. For instance,

# declaring and assigning the var
Marks = 100

# display
print( Marks)

Output:

100

Assigning different values to multiple variables:

Python allows adding different values in a single line with “,” operators.

name, marks, age = "Rabecca Fatima", 80.2, 19

print(name)
print(marks)
print(age)

Output:

Rabecca Fatima
80.2
19

Use of + operator with different variables:

a = 10
b = 20
c = "Hello"
d = "World"
print(a+b)
print(c+d)
print(c+a)

Output:

30
Hello World
TypeError: unsupported operand type(s) for +: 'int' and 'str'

Global and Local Python Variables:

Local variables are those defined and declared within a function. This variable cannot be accessed outside the function.

# This function uses local variable s
def f():
	s = "Hello World"
	print(s)


f()

Global variables are those that are defined and declared outside a function and must be used within one.

# This function uses global variable s
def f():
	print(s)

#Global 
s = "Hello World"
f()

Delete a variable:

We can delete the variable using the del keyword.

x = 6  
print(x)  
# deleting a variable.   
del x  
print(x) 

Output:

6
Traceback (most recent call last):
File "<string>", line 6, in <module>
NameError: name 'x' is not defined

Note: also read about Python operators

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