What does the modulus operator (%) do in Python?

The modulus operator (%) in Python is used to perform a division operation and returns the remainder of that division. For example, when you divide 10 by 3, the quotient is 3, but the remainder is 1. Therefore, using the expression 10 % 3 would yield a result of 1. This operator is particularly useful in programming for tasks such as determining whether a number is even or odd, checking for divisibility, or cycling through values in a loop.

The correct understanding of the modulus operator underlines its role in numerical operations, differentiating it from other arithmetic operations that might either complete the division or summarize values in different ways, such as summation or multiplication.