What does {0} mean in this Python string?

Question

In the following code, {0} is been used in a string and I'm not sure about it and how it works. I can't able to find it anywhere to explaining it

import random

number = random.randint(1, 1000)

guesses = 0

print("I'm thinking of a number between 1 and 1000.")

while True:

   guess = int(input("\nWhat do you think it is? "))

   guesses += 1

    if guess > number:

        print("{0} is too high.".format(guess))

    elif guess < number: 

        print("{0} is too low.".format(guess))

    else:

        break

print("\nCongratulations, you got it in {0} guesses!\n".format(guesses))

Answer 1

It acts as an indicator in the format method that if you want it to be replaced by the first parameter(index zero) of format.

Example : 

print(42+261={0}.format(303))

Here, {0} will be replaced by 303.  

If you want to learn more about Python? Come & Join: python course