Coated paper is coated with an agent to improve the brightness and printing properties as the coating fills the minute pits between the fibres in the paper and usually has a gloss or matt finish.
It’s also very smooth and can either be shiny or have a subtle shine. Whichever finish you choose will affect the outcome of the appearance of the printed item because the ink will sit on the surface. Coated paper is also more dirt-resistant and less affected by moisture and wear making the printed material appear shiny which is why it’s normally used for printing magazines and book covers.
A coated paper tends to restrict the amount of ink that is absorbed by the paper and how the ink bleeds into the paper. Because the ink stays on top of the paper sharp images can be achieved as the ink won’t wick or bleed.