Drupal 8 comes with 74 Core Modules, that come installed “out of the box”. I am going to outline the most used ones.
The Aggregator Module can fetch and display content from other websites – most commonly in the form of RSS. Once enabled, to configure the module go to Configuration -> Aggregator (Under Web Services). Here you can add a feed by entering a URL, Import an OPML file and view all fields currently in use.
Cron assists in the site maintenance, including the indexing of search results, checking for updates for modules and themes and removing temporary files. Once enabled, Cron by default will run every three hours, or you can run Cron manually by going to Configuration -> Cron -> Run Cron.
Enabled by default, the CKEditor and Filter Modules ensure content is structured and markup is clean. They are inspired by Drupal 7’s WYSIWYG and CKEditor modules. By default, CKEditor and Filter allow you to write content in 3 formats: Basic HTML, Restricted HTML and Full HTML. These can be edited in Configuration -> Text Formats and Editors.
The Path Module – enabled by default, allows you to create custom URL aliases for your content. Drupal automatically creates web addresses like
http://www.example.com/?q=node/67 which are not user or search engine friendly. With the use of this module, you can create nicer URL’s that will help you rank up search results.
The Taxonomy Module is enabled by default. It allows you to categorise content with the use of terms and vocabularies. A Vocabulary can be thought of as a Parent of Terms. You could have a Vocabulary as ‘Fruit’ and the terms ‘Apple’ and ‘Banana’. Taxonomies can be added in Structure -> Taxonomy.
The views module (only added to core in Drupal 8) allows administrators and site designers to create, manage, and display lists of content. Each list managed by the views module is known as a “view”, and the output of a view is known as a “display”. Displays are provided as either a block, a page, or both. By default, views may be created that list content, content revisions, or users. Views can also be restricted to certain users via permissions. This means a view for a user admin page, can be made so that it is only accessible to Admin users, and not accessible to any other user. Views can be created in Structure -> Views -> Add View.
You can find more here.