G. Freiman's Theorem is a result in additive number theory that deals with the structure of sets of integers. Specifically, it provides conditions under which a finite set of integers, with a small sum of differences, can be shown to have a certain regular structure. This theorem is particularly useful in understanding how integers can be combined to form sums and how they relate to each other. The theorem states that if a set of integers has a limited number of ways to express sums of its elements, then the set must be close to an arithmetic progression. This insight helps mathematicians analyze and categorize sets of integers based on their additive properties.