Why Linear Regression (aka Ordinary Least Squares and family), repeat from last week

We need first a reminder from last week about linear regression.

Fitting a continuous function with linear parameterization in terms of the parameters \( \boldsymbol{\beta} \).

For more discussions of Ridge and Lasso regression, Wessel van Wieringen's article is highly recommended. Similarly, Mehta et al's article is also recommended.