Here's why:

* Prokaryotes are simple cells that lack a membrane-bound nucleus and other membrane-bound organelles. Their genetic material (DNA) is located in a region called the nucleoid, which is not enclosed by a membrane.

* Eukaryotes, on the other hand, are more complex cells that have a true nucleus containing their DNA, as well as other membrane-bound organelles.

Examples of prokaryotes include bacteria and archaea.