Summarize your words The concept of function, being one of the most important in mathematics, is sometimes misunderstood by students. But what is a function anyway? Just think about the following: whenever we have lui sets and there is some kind of relationship between the set elements j'ai sets, so that every element of the first set is related to a single element of the second set, then we are one in the presence of function. Each of the elements of the first set is called an object and each of the elements of the second set is called an image. Let's suppose that we have a set with five boys and another set with their respective ages, that is, it is a function, since each boy has one and only one age. In this example, each of the boys is an object and their age is an image. In mathematical language there are ways to define a function. No next summary table will show some of the more common ways to represent a function.