A Regression line is a line that describes how a quantitative response variable y changes with change in predictor variable(X).
Linear regression is a machine learning algorithm in which a continuous target variable y is predicted with a linear expression of one or more predictor variables. (X1, X2, …, Xn)
Here, I have mentioned little bit of everything about Linear Regression-
(Linear Regression Expression, Assumptions of Linear Regression, Drawbacks and Python code on how to implement it.)