Simplify the following text for a Grade 4 native English-speaking person.
Original: Today , the term `` BSD '' is often non-specifically used to refer to any of these BSD descendants , e.g. , FreeBSD , NetBSD , OpenBSD or DragonFly , which together form a branch of the family of Unix-like operating systems .
Simplified: There are many different kinds of BSD that many people have worked on . Some of them are NetBSD , FreeBSD , OpenBSD and Mac OS X