An organism is any individual entity that embodies the properties of life. It can be as simple as a single-celled bacterium or as complex as a whale. Organisms can grow, reproduce, respond to stimuli, and carry out various metabolic processes. They are made up of cells, which are considered the basic unit of life.
There are two primary types of organisms: prokaryotes and eukaryotes. Prokaryotes are single-celled organisms that do not have a nucleus or other membrane-bound organelles; examples include bacteria and archaea. Eukaryotes, on the other hand, can be single-celled or multicellular and possess a nucleus and various organelles; examples include plants, animals, fungi, and protozoa. These categories highlight the fundamental differences in cellular structure and complexity among living beings.