If your website platform is a CMS such as Wordpress, Drupal or Joomla it consists of core files and contributed plugins or modules. The core files are the main files for your platform and the contributed ones are optional additions you are using to perform various functions that you require for your particular website. Routinely there are updates available for either the core files or these optional additions that will require updates. Some might just have improved code modifications and some will be security updates.
How do you backup your entire website, what it says and how it looks and responds?
Backing up your files is important if you do not want to risk losing all your data. If you experience a hard drive failure or simply need to restore your computer to its factory state, backing up your files is critical and easy to do.