Here's why:

* Prokaryotes are single-celled organisms that lack a membrane-bound nucleus. 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 organisms whose cells have a true nucleus containing their DNA.

Examples of prokaryotes include bacteria and archaea.

It's important to note that while prokaryotes lack a nucleus, they still have other essential cellular components, such as ribosomes, cytoplasm, and a cell membrane.