A faucet aerator is a small device that is attached to the end of the faucet. Most modern piping fixtures has an aerator that comes along with it. A low flow aerator can be fitted on taps separately as well. It mixes air into the water flow and gives a smoother flow without splashing. Aerators uses less water in the same amount of time, but there is no noticeable change to the use due to the aerated flow.
A faucet or tap aerator is a small round device that is screwed into the end of your tap. It is usually a plastic or wire mesh that can break down the flow of water and introduce air to it. A flow restrictor also might be part of the structure. It is a small disk with a hole in the middle to limit the water flow.
Aerators are the single most effective device in saving water as per studies.