What is the difference between freeBSD and UNIX/LINUX?

actually i am a software developer of mac - windows - mobo devices but i always wonder that what the freeBSD thing is? is it a kernel or an operating system envoirment? if so, then what kind of? and btw i am also confused with the thing that peoples often referred freeBSD as FreeBSD/UNIX. what does it means, does... show more actually i am a software developer of mac - windows - mobo devices but i always wonder that what the freeBSD thing is? is it a kernel or an operating system envoirment? if so, then what kind of?
and btw i am also confused with the thing that peoples often referred freeBSD as FreeBSD/UNIX. what does it means, does it means that unix and freeBSD is the same thing? well, i don't know anything about freeBSD...plz explain it!
3 answers