* Bacteria: These are the most common type of prokaryotes and are found in a wide variety of environments, including soil, water, and the human body. Examples include *E. coli* (found in the human gut), *Streptococcus pneumoniae* (causes pneumonia), and *Cyanobacteria* (blue-green algae that produce oxygen).

* Archaea: These are single-celled organisms that are often found in extreme environments, such as hot springs, salt lakes, and the human gut. Examples include *Methanogens* (produce methane gas), *Halophiles* (live in salty environments), and *Thermophiles* (live in hot environments).

Remember that all prokaryotes are single-celled organisms that lack a nucleus and other membrane-bound organelles.