Dishwasher - Rinse Aid

Rinse aid (sometimes called rinse agent) contains surfactants that uses Marangoni stress to prevent droplet formation, so that water drains from the surfaces in thin sheets, rather than forming droplets.

The benefits of using it are that it prevents "spotting" on glassware (caused by droplets of water drying and leaving behind dissolved limescale minerals), and can also improve drying performance as there is less water remaining to be dried.