Sets
Sets in mathematics, are simply a collection of distinct objects forming a group. A set can have any group of items, be it a collection of numbers, days of a week, types of vehicles, and so on. Every item in the set is called an element of the set. Curly brackets are used while writing a set. A very simple example of a set would be like this. Set A = {1,2,3,4,5}. There are various notations to represent elements of a set. Sets are usually represented using a roster form or a set builder form. Let us discuss each of these terms in detail.
1.  Sets Definition 
2.  Sets Representation 
3.  Sets Symbols 
4.  Types of Sets 
5.  Sets Formulas 
7.  Sets Properties 
8.  Operations on Sets 
9.  FAQs on Sets 
Sets Definition
In mathematics, a set is a welldefined collection of objects. Sets are named and represented using a capital letter. In the set theory, the elements that a set comprises can be any kind of thing: people, letters of the alphabet, numbers, shapes, variables, etc.
Sets in Maths: Examples
We know that a collection of even natural numbers less than 10 is defined, whereas collection of intelligent students in a class is not defined. Thus, collection of even natural numbers less than 10 can be represented in the form of a set, A = {2, 4, 6, 8}. Let us use this example to understand the basic terminology associated with sets in math.
Elements of a Set
The items present in a set are called either elements or members of a set. The elements of a set are enclosed in curly brackets separated by commas. To denote that an element is contained in a set, the symbol '∈' is used. In the above example, 2 ∈ A. If an element is not a member of a set, then it is denoted using the symbol '∉'. Here, 3 ∉ A.
Cardinal Number of a Set
The cardinal number, cardinality, or order of a set denotes the total number of elements in the set. For even numbers less than 10, n(A) = 4. Sets are defined as a collection of unique elements. One important condition to define a set is that all the elements of a set should be related to each other and share a common property. For example, if we define a set with the elements as the names of months in a year, then we can say that all the elements of the set are the months of the year.
Representation of Sets
There are different set notations used for the representation of sets. They differ in the way in which the elements are listed. The three set notations used for representing sets are:
 Semantic form
 Roster form
 Set builder form
Semantic Form
The semantic notation describes a statement to show what are the elements of a set. For example, Set A is the list of the first five odd numbers.
Roster Form
The most common form used to represent sets is the roster notation in which the elements of the sets are enclosed in curly brackets separated by commas. For example, Set B = {2,4,6,8,10}, which is the collection of the first five even numbers. In a roster form, the order of the elements of the set does not matter, for example, the set of the first five even numbers can also be defined as {2,6,8,10,4}. Also, if there is an endless list of elements in a set, then they are defined using a series of dots at the end of the last element. For example, infinite sets are represented as, X = {1, 2, 3, 4, 5 ....}, where X is the set of natural numbers. To sum up the notation of the roster form, please take a look at the examples below.
Finite Roster Notation of Sets : Set A = {1, 2, 3, 4, 5} (The first five natural numbers)
Infinite Roster Notation of Sets : Set B = {5, 10, 15, 20 ....} (The multiples of 5)
Set Builder Form
The set builder notation has a certain rule or a statement that specifically describes the common feature of all the elements of a set. The set builder form uses a vertical bar in its representation, with a text describing the character of the elements of the set. For example, A = { k  k is an even number, k ≤ 20}. The statement says, all the elements of set A are even numbers that are less than or equal to 20. Sometimes a ":" is used in the place of the "".
Visual Representation of Sets Using Venn Diagram
Venn Diagram is a pictorial representation of sets, with each set represented as a circle. The elements of a set are present inside the circles. Sometimes a rectangle encloses the circles, which represents the universal set. The Venn diagram represents how the given sets are related to each other.
Sets Symbols
Set symbols are used to define the elements of a given set. The following table shows some of these symbols and their meaning.
Symbols  Meaning 

U  Universal set 
n(X)  Cardinal number of set X 
b ∈ A  'b' is an element of set A 
a ∉ B  'a' is not an element of set B 
{}  Denotes a set 
∅  Null or empty set 
A U B  Set A union set B 
A ∩ B  Set A intersection set B 
A ⊆ B  Set A is a subset of set B 
B ⊇ A  Set B is the superset of set A 
Types of Sets
Sets are classified into different types. Some of these are singleton, finite, infinite, empty, etc.
Singleton Sets
A set that has only one element is called a singleton set or also called a unit set. Example, Set A = { k  k is an integer between 3 and 5} which is A = {4}.
Finite Sets
As the name implies, a set with a finite or countable number of elements is called a finite set. Example, Set B = {k  k is a prime number less than 20}, which is B = {2,3,5,7,11,13,17,19}
Infinite Sets
A set with an infinite number of elements is called an infinite set. Example: Set C = {Multiples of 3}, which is, C = {3,6,9,12,15 ..........}
Empty or Null Sets
A set that does not contain any element is called an empty set or a null set. An empty set is denoted using the symbol '∅'. It is read as 'phi'. Example: Set X = {}.
Equal Sets
If two sets have the same elements in them, then they are called equal sets. Example: A = {1,2,3} and B = {1,2,3}. Here, set A and set B are equal sets. This can be represented as A = B.
Unequal Sets
If two sets have at least one element that is different, then they are unequal sets.Example: A = {1,2,3} and B = {2,3,4}. Here, set A and set B are unequal sets. This can be represented as A ≠ B.
Equivalent Sets
Two sets are said to be equivalent sets when they have the same number of elements, though the elements are different. Example: A = {1,2,3,4} and B = {a,b,c,d}. Here, set A and set B are equivalent sets since n(A) = n(B)
Overlapping Sets
Two sets are said to be overlapping if at least one element from set A is present in set B. Example: A = {2,4,6} B = {4,8,10}. Here, element 4 is present in set A as well as in set B. Therefore, A and B are overlapping sets.
Disjoint Sets
Two sets are disjoint sets if there are no common elements in both sets. Example: A = {1,2,3,4} B = {5,6,7,8}. Here, set A and set B are disjoint sets.
Subset and Superset
For two sets A and B, if every element in set A is present in set B, then set A is a subset of set B(A ⊆ B) and B is the superset of set A(B ⊇ A).
Example: A = {1,2,3} B = {1,2,3,4,5,6}
A ⊆ B, since all the elements in set A are present in set B.
B ⊇ A denotes that set B is the superset of set A.
Universal Set
A universal set is the collection of all the elements in regard to a particular subject. The universal set is denoted by the letter 'U'. Example: Let U = {The list of all road transport vehicles}. Here, a set of cars is a subset for this universal set, the set of cycles, trains are all subsets of this universal set.
Power Sets
Power set is the set of all subsets that a set could contain. Example: Set A = {1,2,3}. Power set of A is = {{∅}, {1}, {2}, {3}, {1,2}, {2,3}, {1,3}, {1,2,3}}.
Sets Formulas
Sets find their application in the field of algebra, statistics, and probability. There are some important set formulas as listed below.
For any two overlapping sets A and B,
 n(A U B) = n(A) + n(B)  n(A ∩ B)
 n (A ∩ B) = n(A) + n(B)  n(A U B)
 n(A) = n(A U B) + n(A ∩ B)  n(B)
 n(B) = n(A U B) + n(A ∩ B)  n(A)
 n(A  B) = n(A U B)  n(B)
 n(A  B) = n(A)  n(A ∩ B)
For any two sets A and B that are disjoint,
 n(A U B) = n(A) + n(B)
 A ∩ B = ∅
 n(A  B)= n(A)
Properties of Sets
Similar to numbers, sets also have properties like associative property, commutative property, and so on. There are six important properties of sets. Given, three sets A, B, and C, the properties for these sets are as follows.
Property  Example 

Commutative Property  A U B = B U A A ∩ B = B ∩ A 
Associative Property  (A ∩ B) ∩ C = A ∩ (B ∩ C) (A U B) U C = A U (B U C) 
Distributive Property  A U (B ∩ C) = (A U B) ∩ (A U C) A ∩ (B U C) = (A ∩ B) U (A ∩ C) 
Identity Property  A U ∅ = A A ∩ U = A 
Complement Property  A U A' = U 
Idempotent Property  A ∩ A = A A U A = A 
Operations on Sets
Some important operations on sets include union, intersection, difference, the complement of a set, and the cartesian product of a set. A brief explanation of operations on sets is as follows.
Union of Sets
Union of sets, which is denoted as A U B, lists the elements in set A and set B or the elements in both set A and set B. For example, {1, 3} ∪ {1, 4} = {1, 3, 4}
Intersection of Sets
The intersection of sets which is denoted by A ∩ B lists the elements that are common to both set A and set B. For example, {1, 2} ∩ {2, 4} = {2}
Set Difference
Set difference which is denoted by A  B, lists the elements in set A that are not present in set B. For example, A = {2, 3, 4} and B = {4, 5, 6}. A  B = {2, 3}.
Set Complement
Set complement which is denoted by A', is the set of all elements in the universal set that are not present in set A. In other words, A' is denoted as U  A, which is the difference in the elements of the universal set and set A.
Cartesian Product of Sets
The cartesian product of two sets which are denoted by A × B, is the product of two nonempty sets, wherein ordered pairs of elements are obtained. For example, {1, 3} × {1, 3} = {(1, 1), (1, 3), (3, 1), (3, 3)}.
ā Topics Related to Sets:
Check out some interesting topics related to sets.
Examples on Sets

Example 1: Find the elements of the sets represented as follows and write the cardinal number of each set. a) Set A is the first 8 multiples of 7 b) Set B = {a,e,i,o,u} c) Set C = {x  x are even numbers between 20 and 40}
Solution:
a) Set A = {7,14,21,28,35,42,49,56}. These are the first 8 multiples of 7.
Since there are 8 elements in the set, cardinal number n (A) = 8
b) Set B = {a,e,i,o,u}. There are five elements in the set,
Therefore, the cardinal number of set B, n(B) = 5.
c) Set C = {22,24,26,28,30,32,34,36,38}. These are the even numbers between 20 and 40, which make up the elements of the set C.Therefore, the cardinal number of set C, n(C) = 9.

Example 2: If Set A = {a,b,c}, Set B = {a,b,c, p,q,r}, U = {a,b,c,d,p,q,r,s}, find the following using sets formulas, a) A U B b) A ∩ B c) A' d) Is A ⊆ B? (Here 'U' is the universal set).
Solution: a) A U B = {a,b,c,p,q,r} b) A ∩ B = {a,b,c} c) A' = {d,p,q,r,s}
d) A ⊆ B, (Set A is a subset of set B) since all the elements in set A are present in set B.

Example 3: Express the given set in setbuilder form: A = { 2, 4, 6, 8, 10, 12, 14}
Solution: Given: A = { 2, 4, 6, 8, 10, 12, 14}
Using sets notations, we can represent the given set A in setbuilder form as,
A = {x  x is an even natural number less than 15}
FAQs on Sets
What is Sets in Mathematics and Examples?
Sets are a collection of distinct elements, which are enclosed in curly brackets, separated by commas. The list of items in a set is called the elements of a set. Examples are a collection of fruits, a collection of pictures. In another way, sets are represented as follows. Set A = {a,b,c,d}. Here, a,b,c,d are the elements of set A.
What are Different Sets Notations to Represent Sets?
Sets can be represented in three ways. Representing sets means a way of listing the elements of the set. They are as follows.
 Semantic Notation: The elements of a set are represented by a single statement. For example, Set A is the number of days in a week.
 Roster Notation: This form of representation of sets uses curly brackets to list the elements of the set. For example, Set A = {2,4,6,8,10}
 Set Builder Notation: A set builder form represents the elements of a set by a common rule or a property. For example, {x  x is a prime number less than 20}
What are the Types of Sets?
Sets differ from each depending upon elements present in them. Based on this, we have the following types of sets. They are singleton sets, finite and infinite sets, empty or null sets, equal sets, unequal sets, equivalent sets, overlapping sets, disjoint sets, subsets, supersets, power sets, and universal sets.
What are the Properties of Sets in SetTheory?
Different properties associated with sets in math are,
 Commutative Property: A U B = B U A and A ∩ B = B ∩ A
 Associative Property: (A ∩ B) ∩ C = A ∩ (B ∩ C) and (A U B) U C = A U (B U C)
 Distributive Property: A U (B ∩ C) = (A U B) ∩ (A U C) and A ∩ (B U C) = (A ∩ B) U (A ∩ C)
 Identity Property: A U ∅ = A and A ∩ U = A
 Complement Property: A U A' = U
 Idempotent Property: A ∩ A = A and A U A = A
What is the Union of Sets?
The union of two sets A and B are the elements from both set A and B, or both combined together. It is denoted using the symbol 'U'. For example, if set A = {1,2,3} and set B = {4,5,6}, then A U B = {1,2,3,4,5,6}. AUB is read as 'A union B'.
What is the Intersection of Sets?
The intersection of two sets A and B are the elements that are common to both set A and B. It is denoted using the symbol '∩'. For example, if set A = {1,2,3} and set B = {3,4,5}, then A ∩ B = {3}. A ∩ B is read as 'A intersection B'.
What Subsets and Supersets?
If every element in a set A is present in set B, then set B is the superset of set A and set A is a subset of set B.
Example: A = {1,4,5} B = {1,2,3,4,5,6}
Since all elements of set A are present in set B. ⇒ A ⊆ B and B ⊇ A.
What are Universal Sets?
A universal set, denoted by the letter 'U', is the collection of all the elements in regard to a particular subject.
Example: Let U = {The list of all road transport vehicles}. Here, a set of cycles is a subset of this universal set.
What is Complement in Sets?
The complement of a set which is denoted by A', is the set of all elements in the universal set that are not present in set A. In other words, A' is denoted as U  A, which is the difference in the elements of the universal set and set A.
What is Cartesian Product in Sets?
Cartesian product of two sets, denoted by A×B, is the product of two nonempty sets, wherein ordered pairs of elements are obtained. For example, if A = {1,2} and B= {3,4}, then A×B = { (1,3), (1,4), (2,3), (2,4)}.
What is Venn Diagram in Sets?
Venn Diagram is a pictorial representation of the relationship between two or more sets. Circles are used to represent sets. Each circle represents a set. A rectangle that encloses the circles represents the universal set.