Bacteria

Bacteria are ubiquitous, mostly single-celled organisms that form a vast domain of prokaryotic microorganisms. Typically microscopic, they were among Earth's earliest life forms and inhabit diverse environments, from soil and water to extreme locations like hot springs and radioactive waste. Bacteria play crucial roles in nutrient cycling, decomposition, and nitrogen fixation. In hydrothermal vents and cold seeps, extremophile bacteria sustain life by converting dissolved compounds into energy. They also form various relationships with plants and animals, from mutualistic to parasitic. Many bacterial species remain uncharacterized or uncultivable in laboratory settings. The scientific study of bacteria, known as bacteriology, is a branch of microbiology that continues to reveal the complexity and importance of these ancient organisms in both natural ecosystems and human health.