Dexterity is a content type framework for CMF applications, with particular emphasis on Plone. It can be viewed as an alternative to Archetypes that is more light-weight and modular
Dexterity is a system for building content types, both through-the-web and as filesystem code. It is aimed at Plone, although this package should work with plain Zope + CMF systems.
Dexterity is included by default in Plone 4.3 as an alternative to Archetypes and will be the main content type framework in upcoming Plone 5.0.