Which type of fraction has a numerator greater than or equal to its denominator?

An improper fraction is defined as a fraction where the numerator is greater than or equal to the denominator. This means the value of the fraction is either one or greater than one. For example, the fraction 5/4 is improper because 5 (the numerator) is greater than 4 (the denominator). Similarly, 3/3 is also considered an improper fraction since the values are equal.

In contrast, a proper fraction has a numerator that is less than its denominator, indicating that the value of the fraction is less than one. Mixed fractions, on the other hand, consist of a whole number combined with a proper fraction, while simplified fractions refer to those that have been reduced to their lowest terms but do not inherently categorize the relationship between numerator and denominator as in improper fractions. Therefore, the defining characteristic of an improper fraction is precisely why it is the correct answer in this context.