what is HtmlWebpackPlugin in webpack code example

Example: htmlwebpackplugin

//installation
npm install --save-dev html-webpack-plugin

//configuration
var HtmlWebpackPlugin = require('html-webpack-plugin');
var path = require('path');

module.exports = {
  entry: 'index.js',
  output: {
    path: path.resolve(__dirname, './dist'),
    filename: 'index_bundle.js'
  },
  plugins: [new HtmlWebpackPlugin({
      template: "./index.html",
    })]
};