What is a model?
According to google it is “a thing used as an example to follow or imitate” and or a “three-dimensional representation of a person or thing or of a proposed structure, typically on a smaller scale than the original”.
For Merriam the definition is more explored where in point 12 we get a more compatible definition of modelling. “a system of postulates, data, and inferences presented as a mathematical description of an entity or state of affairs; also : a computer simulation based on such a system” Merriam dictionary
Representing our world objects, processes, states as mathematical expressions. These can be developed, visualised and used in CAD, CAE, Excel, Matlab, any capable programable environment software. A good day to day example offered in Merriam dictionary is the Weather model. There are a set of mathematical equations that are calibrated through many real life weather stations that deliver predictions of what the weather will be in the future and what occurred in the past which we did not measure. So basically a model is a means to study a future state or recap a past state through a lot of math. Looks simple.