Sometimes you need to convert between types. Python provides functions for this:
int("42") # String to int: 42
float("3.14") # String to float: 3.14
str(42) # Int to string: "42"
bool(1) # Int to bool: True
Why convert? User input is always a string. To do math with it, convert to int or float first. To concatenate a number with text, convert to string first.
age_str = input("Age: ") # Returns string
age = int(age_str) # Now it's a number
Invalid conversions raise errors. int("hello") fails because "hello" isn't a number.