In this section, we will gain an introduction to viewlets, the snippets of reusable functionality that comprise a Plone page. Items such as breadcrumbs, the logo, the personal bar, and many other items visible on a Plone page are viewlets.
In the following screenshot, you will see a number of unique snippets, or viewlets, that have been labeled:
The following is the list of the viewlets displayed in the previous screenshot and their formal names in the Plone namespace. This list is by no means complete, as you may only see certain viewlets in specific situations, such as on a custom page view or the Contents tab of a folder.
Logo (1):
plone.logo
Global sections (2):
plone.global_sections
Breadcrumbs (3):
plone.path_bar
Byline (6):
plone.belowcontenttitle.documentbyline
History (7):
plone.belowcontentbody.contenthistory
Utility navigation/site actions (10):
plone...