Cells fall into broad categories depending on whether they have a nucleus or not. This is the primary distinction between:

* Eukaryotic cells: These cells have a true nucleus, which contains their genetic material (DNA) enclosed within a membrane. Eukaryotic cells also have other membrane-bound organelles.

* Prokaryotic cells: These cells lack a nucleus and other membrane-bound organelles. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane.

Let me know if you'd like to explore other ways of categorizing cells, such as by their function or their structure!