Uncertainity in determining the outcome of any process, termed as **experiment**, motivates us to analyse the experiment quantitatively by repeating the experiment over and over again to gather the list of all possible outcomes and determine numbers, called **probabilities**, for one outcome or a set of outcomes that tells us the chance, if the experiment was repeated in a similar setting, of that thing to appear again.

What do Roman numerals, Tally marks, Decimal and Binary number systems have in common? They are all used to describe Quantity or the number of things, each with its unique style motivated by a particular usecase.