They are classified as prokaryotes, meaning they lack a nucleus and other membrane-bound organelles found in eukaryotic cells like those in plants and animals.

Despite their simple structure, bacteria are incredibly diverse and play crucial roles in various ecosystems, including:

* Decomposers: Breaking down organic matter.

* Nitrogen fixers: Converting atmospheric nitrogen into usable forms for plants.

* Symbionts: Living in mutualistic relationships with other organisms.

* Pathogens: Causing diseases in humans, animals, and plants.