How to clear the cache using Drush or the user interface.

Overview of the cache and the site data that can be cached.

Overview of logs and where to find recent log messages.

Overview of the status report and where to find it on a site.

How to secure a site by staying informed about the latest security updates.

Overview of security updates, how bugs are handled, and non-security updates.

Overview of cron and how it is different from Unix cron.

How to run cron maintenance tasks using the core Automated Cron module, or by running them from outside the site.

How to update the core software using the administrative interface or Drush.

How to update a contributed module using Composer and the administrative interface for running the Database Updates script.

How to update a contributed theme using Composer and the administrative interface for running the Database Updates script.

How to add a reference field that connects two content types.

How to make content items more presentable.

How to delete a content type that is not required for the site.

How to add and configure a new content type.

How to add fields to a content type.

How to edit a content entry form.

Overview of responsive image styles, which allow you to provide different images for different screen sizes.

How to add an image style to reformat an image.

Overview of image styles and how they are used to display a single image in several variations.