Use the one-word answer as the discount code at checkout. The discount code is reserved for a limited number of riddle-solvers. Each month brings a new puzzle, and a fresh batch of chances to claim the reward.

And don't cheat. The Riddle Master is watching.

I travel through the air, yet have no wings.

I stir your memories with just a trace.

Sometimes, I vanish quickly.

Sometimes, I linger.

What am I?