In mathematics, monomials, binomials, trinomials and polynomials are all algebraic expressions. The expressions that are represented using unknown variables, constants and coefficients, are called algebraic expressions. A variable can take any value, it is not fixed but a constant is a fixed value.
To make these algebraic expressions such as monomials, binomials, trinomials and polynomials, we combine the variables and constants using arithmetic operations (+, , x, ÷). For example, 3x+2 is an expression, which has two parts 3x and 2, separated by the ‘+’ sign. These two parts are called terms here.
What are Terms?
The parts of algebraic expressions that are separated by addition or subtraction, are called terms. The number of terms decides the type of expression, whether it is a monomial, binomial, trinomial or polynomial.
These terms are made of a product of variables and coefficients that are added together to form expressions. For example, 2x and 9 are added together to form the expression: 2x + 9.
Note: A single constant value can also be a term. It is not necessary that a term is a combined form of both variable and constant. In the expression, 3 + 4x, 3 is also a term. 
Also, read: Like and Unlike Algebraic Terms
Factors of Terms
The factors are the value that divides the original value evenly. Thus, the factors of terms are the variables or constants that collectively make the term.
For example, if 4xy is a term, then the factors of 4xy are 4, x and y.
Factors containing variables are said to be algebraic factors. 
What is a Monomial?
A monomial is an algebraic expression that has only one term.
Or we say single term expression is a monomial.
The examples of monomials are:
 12x
 12
 25x
 24y
 4a
 4b
 xy
What is a Binomial?
A binomial is an algebraic expression that has two unlike terms.
Facts:

The examples of binomials are:
 x + y
 m – 5
 mn + 4m
 a^{2} – b^{2}
 xy + 5
 4m – 7n
 3p – 2q
What is a Trinomial?
A trinomial is an algebraic expression that has three terms in it.
The examples of trinomials are:
 x + y + 7
 ab + a +b
 3x 2 – 5x + 2
 m + n + 10
The expression x + y + 3x is not a trinomial as the terms x and 3x are like terms.
What is a Polynomial?
The term poly means many. An expression that has more than one term is called polynomial, nonnegative integral exponents of a variable.
Examples of polynomial expression include:
 ax + by + ca
 x^{3} + 2x + 3
 1.2 ab – 2.4 b + 3.6 a
 1 + x^{2} + xy
Degree of a polynomial
The greatest power or exponent of a polynomial is called its degree.
For example, the degree of x^{3} +x^{2}+x is 3.
Also, check: Degree of a Polynomial
Solved Examples
Q.1 Which of the following are monomials, binomials and trinomials?
 4y – 7z
 ab – a – b
 y^{2}
 100x
 aX+by+cz
 X^{2} + y^{2}
 7mn
 53t
Solution: The respective monomials, binomials and trinomials are:
Monomials 
Binomials 
Trinomials 



Q.2: Add 4x + 3y and x + z.
Solution: Given two binomials, 4x + 3y and x + z.
Adding the given expressions we get;
⇒ (4x + 3y) + (x + z)
⇒ 4x + 3y + x + z
There are two similar terms that can be added. Thus, we get;
⇒ 4x + x + 3y + z
⇒ 5x + 3y + z
Hence, is the answer.
Practice Questions

Frequently Asked Questions – FAQs
What is the difference between monomials, binomials, trinomials and polynomials?
A monomial has a single term, a binomial has two terms, a trinomial has three terms and a polynomial has one or more than one term.
What are the examples of monomial, binomial and trinomial?
The example of a monomial, binomial and trinomial are 3mn, 3mn + x and 3mn + x – y, respectively.
What is the difference between a monomial and a polynomial?
A monomial is also a type of polynomial. But a polynomial is not always a monomial.
Is 5x + 8x a monomial?
5x + 8x is a monomial because 5x and 8x are like terms and can be added.
5x + 8x = 13x
What are the factors of a monomial, 9xyz?
The factors of monomial 9xyz are 9, x, y and z.