A content management system (CMS) is a computer software used to manage the creation and modification of digital content. A CMS is typically used for enterprise content management (ECM) and web content management (WCM). (source google)
A CMS can be custom like
https://www.wplecturer.com/index.php/web-101/cms-custom
or can be Open Sources like WordPress, Joomla, Drupal, or more
the last category
- has blocks of code plugins/extensions FREE and PRO
- Themes FREE and PRO
- you can build a site very fast with WordPress or Joomla
- or very secure with Drupal (it is more difficult)
- and more
Here is a link for FREE WordPress Tutorials
https://www.wplecturer.com/index.php/cms-blogs/wordpress
