Development environments provide a sandbox where you can work on your application without affecting the live site.

Drush is a command line interface that enables you to interact with your Drupal site without clicking around the graphical user interface (GUI).

A block is a reusable widget that is placed inside regions (layout containers) of your theme. Blocks can be used by site administrators on the Block layout admin page or provided by a module using the Plugin API.

Content modeling consists of identifying and constructing the different building blocks of data that compose the information on your site.

A layout can describe how various components are arranged on various levels—from an entire page from the header to the footer, to just the “middle” where the dynamic content goes, to individual components. It can apply to templates for managed content or one-off designs for landing pages.

A content type is a subtype of the [content entity](link to Entity topic). When a content creator goes to add new content to the site, they are presented with a list of content types to choose from to get the appropriate form to fill out.

Comments are a content entity type that allows users to leave commentary associated with a specific piece of content.

Devel is a popular developer module containing a variety of developer and debugging utilities including Webprofiler, Devel generate and Kint.

A site’s main navigation elements, whether they be in the header, footer, or sidebar, are composed of links built using Drupal's menu system. Drupal allows site administrators to build menus while also allowing module developers to add and alter menus in code.

Learn to use data from your Drupal site to create customized lists in various forms, such as bulleted lists, grids, calendars, or sliders.

Entities are the fundamental building blocks that make up any Drupal site. Having a good understanding of the Entity system is an important part of ensuring the data model of your Drupal site is set up properly.