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Definition of a Set
A set is a well-defined collection of distinct objects, called elements or members of the set. Sets are
typically denoted by capital letters such as A, B, or C, and their elements are listed within curly braces {}.
For example, the set A = {1, 2, 3} is a collection of the numbers 1, 2, and 3.
An object x is said to be an element of set A if x belongs to A, written as x ∈ A. If x does not belong to A, we
write x ∉ A. For instance, if A = {1, 2, 3}, then 2 ∈ A but 4 ∉ A.
Set Notation Element Notation Not an Element
A = {1, 2, 3} x ∈ A (x belongs to A) x ∉ A (x does not belong to A)
