MacPorts has a unique ability to allow multiple versions, revisions, and variants of the same port to be installed at the same time, so you may test new port versions without uninstalling a previous working version.

This capability derives from the fact that a MacPorts port by default is not installed into its final or “activated” location, but rather to an intermediate location that is only made available to other ports and end-users after an activation phase that extracts all its files from the image repository. Deactivating a port only removes the files from their activated locations (usually under ${prefix})—the deactivated port's image is not disturbed.

The location of an installed port's image can be seen by running:

%% port location PORTNAME