What are bacteria primarily characterized as?

Bacteria are primarily characterized as microscopic organisms that can be either pathogenic or beneficial. They are unicellular and are typically too small to be seen without a microscope. This characteristic allows them to inhabit a wide range of environments, from soil and water to the human body.

Some bacteria are known for their ability to cause diseases, making them pathogenic. These harmful strains can lead to infections in humans, animals, and plants. On the other hand, many bacteria play essential roles in various ecosystems and are beneficial; for instance, they aid in digestion in the human gut, contribute to nutrient cycling in the environment, and are involved in processes such as fermentation in food production.

This distinction highlights the versatility and importance of bacteria in both positive and negative contexts, which is a critical aspect of understanding their role in biology and health.