This site links to various documentation sources for Zope and related software.
The Zope web application server, formerly called Zope 2, is under active development. The latest major release was version 5.
The ZODB object database is the default storage engine for Zope.
Zope Toolkit (ZTK)
The Zope Toolkit represents the various library packages that were created for Zope 3/Bluebream. Many of them live on in Zope itself.