Precompiled (binary) ports are called packages. A package can be obtained from the corresponding port with make package command; prebuilt packages are also available for download from the FreeBSD servers. A user can automatically install a package by passing the package name to the pkg_add -r command. This downloads the appropriate package for the user's release version of FreeBSD, then installs the application along with any software dependencies it may have. By default, this command downloads packages from the main FreeBSD distribution site.
FreeBSD maintains a build farm called the pointyhat cluster in which all packages for all supported architectures and major releases are built. The build logs and known errors for all ports built into packages through the pointyhat cluster are available in a database.
These precompiled packages are separated into categories by the architectures for which they are available. Packages are further separated into several "release" directories, one for each current production release built from the ports collection and shipped with the release. These production release directories are never updated.
There are also stable and current directories for several major release branches. These are updated more or less weekly. In most cases a package created for an older version of FreeBSD can be installed and used on a newer system without difficulty since binary backward compatibility across major releases is enabled by default.
Read more about this topic: Free BSD Ports