Prokaryotic organisms are simple, single-celled life forms that lack a nucleus and other membrane-bound organelles. They are classified into two main groups: bacteria and archaea. These tiny organisms can be found in various environments, from soil to extreme conditions like hot springs, and they play essential roles in ecosystems, such as decomposing organic matter and fixing nitrogen. Despite their simplicity, prokaryotes are incredibly diverse and adaptable. They reproduce quickly through a process called binary fission, allowing them to thrive in many habitats. Some prokaryotes are beneficial to humans, like those used in fermentation for making yogurt, while others can cause diseases.