There may be situations in our real life programming where we need to skip a segment or set of statements and execute another segment based on the test of a condition. This is called alternative or branching.

A program statement that causes a jump of control from one part of the program to another is called control structure or control statement.

Syntax:
if < condition >:
          statements-block 1
else:
          statements-block 2

There are three important control Structures
(i) Sequential
(ii) Alternative or Branching
(iii) Iterative or Looping

range (1,30,1) - will start the range of values from 1 and end at 29
range (2,30,2) - will start the range of values from 2 and end at 28
range (30,3,-3) - will start the range of values from 30 and end at 6
range (20) - will consider this value 20 as the end value(or upper limit) and starts the range count from 0 to 19 (remember always ranget) will work till stop -1 value only)

i= 10 # intializing part of the control variable
while (i<=15): # test condition
print (i, end='\t') # statements - block 1
i=i+1 # Updation of the control variable
else:
print ("\n Value of i when the loop exit",i)
Output:1
10 11 12 13 14 15
Value of i when the loop exit 16

for var in sequence:
# code inside for loop
if condition:

while test expression:
#code inside while loop
if condition:

Syntax :
      while <condition>;
                statements block 1
       [else:
                statements block2]

Multiplication table :
num =int(input("Enter the number: "))
print("multiplication Table of", num)
for i in range(1,11):
        print (num,"x",i, "= ",num*i )
Output :
Enter the number : 6
Multiplication Table of 6
6 x 1 = 6
6 x 2 = 12
6 x 3 = 18
6 x 4 = 24
6 x 5 = 30
6 x 6 = 36
6 x 7 = 42
6 x 8 = 48
6 x 9 = 54
6 x 10 = 60.

for i in range (100, 1000):
     if a%2==1:
              print b
Output :
101,103,105,107,...........,997,999