Articles Field by Regular Labs is a Joomla! custom field plugin that greatly extends the capabilities of custom fields.

With the native Joomla! lists fields, the values are only treated as plain text and cannot be linked to any other content.

The main "Articles" Field type (articles) plugin is a custom field that gives you the ability to choose from a list of articles (based on the selected filters), allowing you to directly connect articles to each other.

The result displayed on the frontend article is a list of the selected articles, that can be hyperlinked to the respective articles, and even displayed with a custom layout (title, custom fields, and other article data).

You can determine which articles show up in the custom field select list by optionally filtering it by categories. The Pro version allows you to also filter the list of articles by tags, authors, language, and other custom field values.

The Pro version also comes with an additional plugin: the "Articles - Linked" Field type (articleslinked) .
The "Articles - Linked" Field type adds the ability to automatically show, in an article, all the articles that are linked to it via instances of the "Articles" Field. This makes it possible to have both articles automatically link back and forth to each other.