All living creatures are classified into systems and sub-systems based
on their similar characteristics. They are divided from bigger groups
into smaller groups based on the detail of their similarities i.e. how
they look, move, reproduce and how they relate to each other. A
practical way of understanding the classification of living organisms is
that organisms are linked to other similar organisms via family trees.
The classification of all living creatures includes at least four
levels: order, families, genus and species.
