1. Bacteria are microscopic, unicellular, prokaryotic organisms belonging to the kingdom Monera.
2. Some bacteria are solitary with independent existence. Some are colonial forms.
3. The bacterial cell lacks well-formed nucleus with nuclear membrane and cell organelles.
4. Reproduction is by binary fission.
5. In favourable conditions, bacteria duplicate with a great speed. Within 20 minutes they can double in number.
6. Bacteria may be round as in Cocci, elongated as in Bacillus, comma shaped as in Vibrio and spiral shaped as in Spirillum.
