Sets in Python are mutable, which means we can add new elements to them even though the items themselves must be immutable.

add( ) method :
           The add( ) method inserts one element into the set 
           If the value is already present , it is ignored .
 
Python 
fruits = {"apple", "banana"} fruits.add("mango") print(fruits) #output {'apple', 'banana', 'mango'} #order may change

update( ) method :
           The update method can add multiple values from lists, tuples, another set etc. 
           
Python 
numbers = {1, 2, 3} numbers.update([4, 5, 6]) print(numbers) #output {1, 2, 3, 4, 5, 6}

Add characters from String :

Python 
s = set() s.update("python") print(s) #outout {'p', 'y', 't', 'h', 'o', 'n'}