What is a composite, prime, and …

Composite Numbers -

A composite number is a positive integer that has a factor other than 1 and itself. For instance, 12 is a composite number because it is a positive integer and it has factors other than 1 and itself. 2, 3, 4, 6 are its factors other than 1 and itself. All even numbers greater than 2 are composite numbers. 2 is a prime number. The smallest composite number is 4.

Prime numbers:

Numbers which have only two factors 1 and the number itself are called prime numbers.

E.g 2 ,3 ,5, 7 ,11 ,13, 17 and so on are all prime numbers.

Of the first 100 numbers 25 are prime numbers.

Only 2 is an even prime number all prime numbers are odd.

Co prime numbers:

Numbers which do not have any common factor between them other than one are called coprime numbers.

Two natural numbers( not necessarily Prime) are coprime if their HCF is 1.
For e.g 
(1,2) , (1,3), (3,4), (3,10), (3,8), (5,6), (17,23)

even two composite numbers can also be Prime. for e.g
(16,25), (84,65)