Laravel Mix provides a fluent API for defining Webpack build steps.https://github.com/JeffreyWay/laravel-mix
Q : What is webpack ?
A : Webpack is a module bundler and also capable of transforming, bundling, or packaging just about any resource or asset
Source : http://github.com/webpack/webpack
More : https://webpack.js.org/
First, why the need of webpack ?
Very well explained in link below
Next, why the need of laravel-mix ?
Short answer : Simplicity over complexity
Laravel mix provides simple wrappers around webpack to provide default configs to hide multiple configs of webpack.
With a single line of code, Laravel Mix allows you to trigger a number of vital actions.