Aerators are small attachments that screw onto the end of taps. They mix air into the water stream and control flow, so you use less water without necessarily noticing a big difference in how it feels.
Instead of a heavy, splashing stream, you get a softer, more controlled flow that’s still perfectly fine for washing hands, brushing teeth or rinsing dishes. Most people don’t feel deprived; they just notice less splashing and sometimes a nicer flow.
Because aerators are inexpensive and easy to install, they’re a simple way to cut down water use at multiple sinks in your home. Over months and years, that reduced flow adds up on your bill and is kinder to local water resources.
You still have the convenience of taps as usual, just with less waste every time you turn them on.