The Zope Object Database provides an object-oriented database for Python that provides a high-degree of transparency. Applications can take advantage of object database features with few, if any, changes to application logic. ZODB includes features such as a pluggable storage interface, rich transaction support, and undo.
The .tgz file is the source tarball. You must have a C compiler to build the software from this file. The .exe files are pre-built Windows installers - you need to get the one specific to the major.minor version of Python you use on Windows.
ZODB3 3.5 requires Python 2.3.5 or later; Python 2.4.1 or later is recommended.
Current Zope 3 development is using ZODB 3.6. ZODB 3.5 cannot be used with Zope 2.7 or earlier. Zope 2.8 uses ZODB 3.4 and Zope 3.1 uses ZODB 3.5.
For more information, see the following resources: