https://www.youtube.com/watch?v=AqD4Q-hWVc8

Levelling is the process of determining the change in elevation between points. It is a is a process of determining the height of one level relative to another.

It is used in surveying to establish the elevation of a point relative to a datum, or to establish a point at a given elevation relative to a datum.

Rise and Fall Method
It consists of determining the difference of elevation between consecutive points by comparing each point after the first that immediately preceding it in the direction of travel.

On this video we have solved a typical levelling problem using the rise and fall method of levelling computation in surveying.