What is notations?

Answer 1

Please be more specific. Do you mean scientific notation?

Answer 2

A notation is a particular way of writing something in maths (or otherwise), which gives clear illustration of the desired meaning. Generally notations are universally accepted, although sometimes they are not, and they are usually easy to write. It is definitely easier to show some examples of notation:

X2 is how we write "X squared", which as I'm sure you know is the same as X*X

This is power notation, we write "X to the power of any number a" as "Xa".

When calculating rates of change, gradients etc, we have two commonly used notations:

dy/dx is the Leibniz notation for the differential of y with respect to x, or in other words the rate of change of the variable y with respect to x. Another way of writing the same thing, using a different notation, is Newton's notation. Newton wrote y' as the derivative of y. In this case both "notations" are taken to mean the same thing, depending upon the situation both could be and are used.

The concept of notation can appear anywhere. All it means is to use symbols, letters or even sometimes diagrams or pictures to express a meaning.