Bacillus subtilis, Microbe of the Year 2023, is a rod-shaped bacterium the most striking characteristic of which is the formation of extremely robust survival stages, the endospores. They withstand extreme heat as well as dehydration and radiation and can remain viable for many millions of years. The formation of endospores is embedded in a complex differentiation program that combines many different survival strategies with the multicellular mode of life in bioflms. This diversity of microbial life makes B. subtilis unique. It also provides important biotechnological applications, such as the production of detergent enzymes or the addition of endospores as probiotics in animal feed. In addition, B. subtilis is also used for the production of vitamins or for the self-healing of concrete. B. subtilis is as diverse in its natural microbial life style expressions as is its universal applicability as a „workhorse“ of biotechnology for the beneft of mankind. For all of these reasons, this bacterium has rightly been selected Microbe of the Year 2023.