Prime factorisation is a method to find the prime factors of a given number, say a composite number. These factors are nothing but the prime numbers. A prime number is a number which has only two factors, i.e. 1 and the number itself.
For example, 2 is a prime number which has two factors, 2 × 1. Whereas a composite number has more than two factors present in it. For example, 4 has three factors such as 1 × 2 × 2.