On-ear headphones sits directly against your ears and don't completely cover the ear. These are mainly made with travel in mind. The ear cups are smaller than over-ear headphones. On-ear headphones have larger drivers than in-ears, meaning that in the same quality and price range, they can typically reproduce a wider range of frequencies.
The padded ear cups and the light sound absorption from the outside make these headphones an all-rounder for any occasion.