FreeBSD: Update and Upgrade

Updating, or applying security patches, is quite straightforward:

freebsd-update fetch
freebsd-update install

The first command will determine if any outstanding patches are available, and if so, will list the files that will be modified if the patches are applied. The second command will apply the patches.

Upgrades are divided in two types: minor and major upgrades:
- Upgrades from one minor version of FreeBSD to another, like from FreeBSD 10.1 to FreeBSD 10.2, are called minor version upgrades;
- Upgraded from one major version to another, like from FreeBSD 9.X to FreeBSD 10.X, are called major version upgrades.
Both types of upgrades can be performed by providing freebsd-update with a release version target:

freebsd-update -r 10.2-RELEASE upgrade

References:
- https://www.freebsd.org/doc/handbook/updating-upgrading-freebsdupdate.html