Factorization is the resolution of an entity into factors such that when multiplied together they give the original entity. By entity we mean any value either a number or algepric expression. For Example, you want to know factors of 6 which can be 3 and 2. Further more, factors for 18 can be 2,3,3 or 9,2 or 3,6 and 18,1.

The First thing to learn here is how to start. For numeric values i.e numbers, start by dividing the least possible value which is 2 then with 3 and so on. once you have LCM of the value. use them to create different factors. For example for 18 LCM values are 2,3,3. Now mutiply 2 and 3 makes 6 and what is left is 3 so another pair is 6 and 3. similarly leave 2 and multiply 3 with other 3 which gives 9 so we got another pair which is 2 and 9.