An efflux pump is an active transporter in cells that moves out unwanted material. Efflux pumps are an important component in bacteria, particularly in their ability to remove antibiotics. The efflux process can also involve the movement of heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals, bacterial metabolites, and neurotransmitters. All microorganisms, with a few exceptions, have highly conserved DNA sequences in their genome that encode efflux pumps. Efflux pumps actively move substances out of a microorganism, in a process known as active efflux, which is a vital part of xenobiotic metabolism. This active efflux mechanism is responsible for various types of resistance to bacterial pathogens within bacterial species, the most concerning being antibiotic resistance, as microorganisms can have adapted efflux pumps to divert toxins out of the cytoplasm and into extracellular media.