why migration use in laravel code example

Example 1: php artisan make migration

php artisan make:migration create_users_table

Example 2: laravel migration artisan

/**
 * The database connection that should be used by the migration.
 *
 * @var string
 */
protected $connection = 'pgsql';

/**
 * Run the migrations.
 *
 * @return void
 */
public function up()
{
    //
}