Horizontal and vertical writing in East Asian scripts

Many East Asian scripts can be written horizontally or vertically. Chinese characters, Korean hangul, and Japanese kana may be oriented along either axis, as they consist mainly of disconnected logographic or syllabic units, each occupying a square block of space, thus allowing for flexibility for which direction texts can be written, be it horizontally from left to right, horizontally from right to left, vertically from top to bottom, or even vertically from bottom to top.

Source: Wikipedia — Horizontal and vertical writing in East Asian scripts (CC BY-SA 4.0)