A parameter is a quantity that influences the output of a model and can be constant or variable. When variable, the range of possible values identifies a collection of distinct cases in a problem. In most of mathematical problems, parameters are held constant, while in statistical problems parameters adopt a range of values and are variable. For example, in an ordinary regression model, parameters are deterministic and are just represented by a number. In contrast, in a Bayesian linear regression model, parameters have statistical distributions and can adopt a range of values. In simpler cases, a parameter represents “a definable, measurable, and constant or variable characteristic, dimension, property, or value, selected from a set of data (or population) because it is considered essential to understanding a situation (or in solving a problem).” Mean and standard deviation of a measurable characteristic of a population are examples of parameters in such cases. Similarly, in the context of fragilities, typically fragility parameters are median and dispersion of a LogNormal distribution defining the fragility. Captured from: (https://www.britannica.com/topic/parameter; https://mathinsight.org/definition/parameter; http://www.businessdictionary.com/definition/parameter.html)