What do I clean my new 27inch iMac screen with?

Displays

Disconnect the display from power, from its connection to a computer, and from any external devices. Next use the cloth that came with your display or another soft, dry cloth to wipe dust from the screen. If additional cleaning of the display panel or case is required use a soft, slightly damp, lint-free cloth. Avoid getting moisture in openings. Don’t use window cleaners, household cleaners, aerosol sprays, solvents, alcohol, ammonia, or abrasives to clean the display.

Warning: Don’t clean the screen with a cleaner containing alcohol or acetone. Use a cleaner intended for use with a screen or display. Never spray cleaner directly on the screen. It may drip inside the display and cause damage.