Bacteria,archaea and eukarya make up the three domains of life. Because of the significant differences were discovered between bacteria and archaea scientists come up with the three-domain system of categorization.
Members of bacteria and archaea still have many similarities. The most significant similarity is that they are both prokaryotes. It means they are single-celled organisms that do not have a nucleus. Archaea and bacteria are both microscopic, which means they cannot be seen without the aid of a microscope. In addition, both archaea and bacteria move by using flagella. Flagella are small structures that the organism uses to throw themselves through their environment.
