Here's why:

* Prokaryotes are single-celled organisms that lack a membrane-bound nucleus and other membrane-bound organelles. Their genetic material (DNA) is located in a region called the nucleoid, but it's not enclosed within a membrane.

* Eukaryotes, on the other hand, have a nucleus that contains their DNA. They are more complex organisms that can be single-celled (like amoebas) or multicellular (like plants and animals).

Examples of prokaryotes include bacteria and archaea. They are incredibly diverse and play crucial roles in ecosystems, from decomposing organic matter to fixing nitrogen.