The two major types of cells in the human body are prokaryotic cells and eukaryotic cells. Prokaryotic cells, such as bacteria, are simpler in structure, lacking a defined nucleus and membrane-bound organelles. In contrast, eukaryotic cells, which include plant and animal cells, have a more complex organization with a well-defined nucleus and various organelles performing specialized functions. Eukaryotic cells are generally larger than prokaryotic cells and are responsible for the functions of multicellular organisms. Understanding these cell types is fundamental to biology and medicine, as they represent the basic building blocks of life.