A prokaryote is a simple, single-celled organism that lacks a nucleus and other membrane-bound organelles. They are typically smaller than eukaryotic cells and have a more straightforward structure. Prokaryotes are classified into two main groups: bacteria and archaea. They reproduce asexually through a process called binary fission. Prokaryotes play essential roles in various ecosystems, including nutrient cycling and decomposition. They can be found in diverse environments, from soil to extreme conditions like hot springs. Some prokaryotes are beneficial, such as those used in fermentation and biotechnology, while others can cause diseases in humans and animals.