Many people take this theme and modify the PHP template files, CSS, functions.php, etc. to meet their exact needs. If you do this, and then later update/upgrade to a newer version of the theme, then you will lose your changes.
Because of this, if you do intend to modify the template in any way, I recommend you create a «child theme». With your child theme, you can change any PHP file, CSS file, etc, and if you later update the site, your changes won’t be affected.
Creating a child theme actually is very simple. Please go here to learn how to do this.