This is an excellent introduction to FreeBSD ports system.
From the article:
We present the main features of the FreeBSD ports system, explaining how it is structured, how software is installed and updated, and compare it with the Debian system.
The FreeBSD ports system is a complex collection of tools and data files allowing to retreive, compile and install software packages on a computer in a coherent way. One can also install precompiled software packages. Finally there are tools allowing to maintain the installed software in current state. This system has been invented by one of the founders of the FreeBSD project, Jordan Hubbard, and checked in CVS in 1993
(Found via amazingdev blog)