For each content entity type there are multiple View modes. A View mode is a specific view of the content. For example, you can view an Article in Full or as a Teaser. The Full view mode is typically used when the content is displayed on its own page. The Teaser view mode is a short format that is typically used in lists of multiple content items. 

Drupal provides a number of different View modes and you can create additional ones if you require. View modes are created and managed under Structure > Display modes > View modes.

Types of view mode

There are two types of View mode, each with specific options:

Full content view mode 

Used to display the content in full on its own page.

• You can only have one Full view mode per type of content. For example, there's only one Full article view mode.
• You can have multiple templates for the Full view mode.

All other types

Used to display a different (non full) view of the content.

• You can have as many other types of View mode as you like.
• You can only have one template for each "non full" View mode

Understanding view modes