Dynamic websites retrieve the contents on the fly and assemble them to a web page every time someone visits the website. A caching server stores these web pages so future requests can be served faster. This helps the server respond to more requests and keep the system from slowing down.
Short for Command Line Interface. A software that has no GUI. The user issues commands to the program in the form of successive lines of text. There has been one very popular CLI tool for Drupal for many years: Drush, short for Drupal Shell. Starting with Drupal 8 a second CLI tool has been introduced called Drupal Console. Those CLI tools are used by developers and administrators, ordinary Drupal users will most likely never get in touch with them.
Short for Content Management System. A CMS is an application that lets you administrate digital content without any technical knowledge. It often contains features like user management, access control, content editing, file management and page composition.
Composer is a dependency manager for PHP, the programming language Drupal is written in. It allows to automatically install and update third-party packages and libraries that are used in an application together with their dependencies. Composer can also be used to update Drupal core and contributed modules. Reusing third-party code from other developers reduces costs and provides access to mature solutions that have been tested and improved by many programmers.