In mathematics, an expansion of a product of sums expresses it as a sum of products by using the fact that multiplication distributes over addition—the opposite process of trying to write an expanded polynomial as a product is called polynomial factorization. Expansion is the act of expanding, mathematically speaking; it is removing all the brackets present in the expression. Usually, in math, we encounter a few expression where they place two sets of two terms, both in brackets side by side like this (a+b)(a-b).This requiring removing brackets and simplification. The act of expanding or the state of being expanded. Something expanded; an expanded surface or part. The degree, extent, or amount by which something expands—an increase, enlargement, or development, especial in the activities of a company. An example of an expansion is an extra three rooms built onto a house. Expand is defined as to increase in size, unfold or spread out. An example of expanding is someone making friends at a party. An example of expanding is a pregnant woman's belly. An example of expanding is someone gathering more knowledge about a topic.