Almost all trilobites had a similar body: a cephalon (head end), thorax (middle section) and pygidium (tail).
However, there were exceptions (see Naraoia).
Note that the name 'trilobite' does not come from this three-section head-to-tail structure.
It is derived from the three lobes seen from side to side, being the left, central and right lobes, which were formed by two furrows or divisions running from head to tail.