Here's a breakdown:

* Anaerobe: An organism that can live and grow in the absence of oxygen.

* Facultative: Meaning "optional." This refers to the ability to switch between different modes of metabolism depending on the environment.

Facultative anaerobes have the ability to use oxygen for respiration if it is available, but they can also survive and grow by using other processes, such as fermentation, when oxygen is scarce or absent.

Examples of facultative anaerobes include:

* Yeast: Used in baking and brewing.

* E. coli: A common bacterium found in the human gut.

* Staphylococcus aureus: A bacterium that can cause skin infections.