The two main types of cells in the human body are prokaryotic cells and eukaryotic cells. Prokaryotic cells are simpler, smaller, and do not contain a nucleus or membrane-bound organelles. They primarily exist as bacteria, which can be found in various environments and even within the human body. Eukaryotic cells, on the other hand, are more complex and larger, characterized by a defined nucleus and organelles, including plant and animal cells. The human body is made up of numerous eukaryotic cells, which perform specialized functions essential for life.