What does the set union symbol represent?

The set union symbol represents the combination of all elements from two or more sets, including every unique element without duplication. When you perform a union of two sets, it encompasses all the numbers from both sets, ensuring that if an element is present in either set, it appears in the resulting set.

For instance, if Set A contains the numbers {1, 2, 3} and Set B contains {3, 4, 5}, the union of these sets will yield the set {1, 2, 3, 4, 5}. Notice that the number 3, which is common to both sets, only appears once in the result. This shows how the union operation includes all unique elements from both sets.

In contrast, options that refer only to elements from the first set, common numbers, or elements in neither set do not accurately reflect the definition of set union. The union is specifically inclusive of all numbers from both sets, making it a fundamental operation in set theory.