An analogy I once read is that the port is a 'skeleton' of what is needed to build the application. The source code still needs to be fetched to build it.
The FreeBSD Ports Collection offers a simple way for users and adminis-
trators to install applications. Each port contains any patches neces-
sary to make the original application source code compile and run on BSD.
The Makefile automatically fetches the application source
code, either from a local disk or via FTP, unpacks it on your system,
applies the patches, and compiles it.