What is an aerator?
An aerator is a way of introducing air into some process or other. Probably the most common is in your home faucet. Instead of a stream of "solid" water, your faucet probably has a little collar with a fine mesh grid that breaks up that solid stream of water and introduces air into it. You still get the same water pressure, but the actual volume is reduced, so you save water that way.
But there are many forms of aeration. If you have a giant vat of taffy or bread dough, there are probably giant paddles to stir it around to fold air into the mixture.
You can find aerators in fish tanks to. My fish tank has an aerator pump, that can oxygenate 342 gallons of water an hour and filter it. When the aeration valve is off it can pump and filter 400 gallons of water, due to the air introduced into the stream of water is off and not displacing the other 58 gallons of water.
An Aerator is also a tool used to aerate your lawn. This type of machine will make holes in your lawn and leave cores. It is called and aerator because it makes it easier for air and water to access the soil roots.
You also have aerators that can be used for making wine