Prokaryotes are one of the most prodigious and one of the simplest forms of life on the planet. They are principally characterised by a complete absence of large membrane bound organelles that are present in eukaryotes. Prokaryotes are also smaller (0.5 –5 micrometers long) compared to eukaryotes, which can be up to 40 micrometers long. Prokaryotes do not have a nucleus and their DNA floats freely in the cytoplasm as many plasmids.
Prokaryotes can have a great many features that a basic eukaryote generally does not have. Some secrete about themselves a slime capsule (principally for protection). Some can manipulate their plasma membrane to create proto-organelles for photosynthesis, or nitrogen fixation. Some grow villi, others, flagellum.
Prokaryotes are bacteria, or archaea, they do not exist as defacto multicellular organisms but often form colonies.