Customizable

The base installation of FreeBSD is, very purposefully, lean and mean - it contains very few pre-installed services other than those absolutely necessary to operate the machine. FreeBSD sysadmins are encouraged instead to install their own services, whether from the ports tree or elsewhere, choosing for themselves which software packages suit their needs best.

For example, any given webmaster will of course need a webserver - but for different situations, different types of webserver are more or less appropriate. Some may need the compatibility with older plug-ins of the Apache 1.x family, while others will want the greater security and speed of the Apache 2.x family, and others yet may need the ultimate speed and efficiency (at the sacrifice of CGI capability) of the thttpd family - and under FreeBSD, it is very easy and "normal" to use any or all of the above, or even switch between them with minimal pain and heartache.

This is not just true of webservers, but also FTP, DNS, mail, ssh, X-Windows components, and just about anything else you care to name. Even those services which do have a default system installation (such as sendmail for mail services) are specifically designed to be simply and easily replaced in a modular fashion with any alternate service that the system administrator may choose; for example you may replace sendmail with qmail with a single command: cd /usr/ports/mail/qmail && make install && make disable-sendmail && make install-qmail clean. (Of course, you'd also need to configure qmail after doing that, so don't just blindly replace sendmail now after reading this line unless you're ready to learn a new system.)

This is in stark contrast not only to Microsoft Windows, in which you are generally bound with iron chain to whatever Microsoft provided you in the way of system services, but also to many GNU/Linux variants. For example, veteran Red Hat Linux admins are very familiar with the idea that Apache 1.x "goes with" Red Hat 7, whereas Apache 2.x "goes with" Red Hat 8, and it can be something of a dire mess to try to change from one to the other - and upgrading your base system is likely to willy-nilly change your services whether you want it to or not.

FreeBSD tries, and in general succeeds pretty well, in drawing a more concrete line between the base system and optional services. Not only is it easy to install whatever type of service you like from whichever vendor or group that you like, you don't have to sweat that upgrading your version of FreeBSD will suddenly make the service you depend on inoperable either.