Ecchi - a genre of anime that demonstrates various hints of sexual relationships, but the relationships themselves are not shown. Now Ecchi is widely used in various anime genres in the form of fanservice - various hints at erotica (mostly this is related to girls characters). This could be special angles of view in the frame, where you can see the character's underwear, awkward situations and ambiguous poses, accents on the chest or buttocks, and so on.
Some anime in this genre may have an age restriction of 18 years.
