A mathematical equation used to describe the association between one or more independent explanatory (predictor) variables and one or more response variables, used to estimate/predict the responses for given values of the predictors. Also known as Prediction equation.
A typical linear model can take the following form:
Y = a + bX + ε
Y = the response variable
X = the predictor variable
a = the constant mean term
b = the regression coefficient showing the change in X for a unit increase in Y
ε = the error term