Modern Korean is often written horizontally from left to right. When the writing space is long vertically but limited horizontally, vertical writing is utilized. The basic unit of language expression is the word, and each word is composed of one or more characters. There are many different ways to write characters.
Traditional Chinese is usually written vertically from top to bottom. However, in order to make more space for the writing, Chinese characters are sometimes split into two parts: a radical and a phonetic element. The two elements are brought together when they are needed in order to create a new character. For example, the character "人" (person) is made up of the radical "人" and the phonetic "氏" (clan).
Korean uses a unique system of han'gŭl to write words. Each syllable has a corresponding logographic character that can be used to write a whole sentence. Han'gŭl was developed in the 4th century AD by Buddhist monks in what is now South Korea. It's based on the native alphabets of China and Japan at that time. These alphabets were using phonetic symbols which were later incorporated into Chinese characters.
Chinese, Japanese, and Korean are more adaptable and can be written from left to right or vertically from top to bottom (with vertical lines proceeding from right to left). In Chinese publications, for example, both orientations can sometimes be mixed on a single page.
Because of this similarity, the direction in which characters are written is called "directionality". Characters are always read in order, from top to bottom and left to right. However, some characters are written with their components drawn from different directions (such as 日 for its Japanese reading), so they can be interpreted differently depending on the direction in which they are read.
Korean has no specific directionality regarding writing, but most words are read from left to right. Some adjectives, however, may be read either way depending on the context; for example, "나쁜" ("napchae") means "bad", but "나우" ("naou") means "good".
The only way to determine the reading direction of a word is by looking at the character(s) used to write it. For example, "김" ("kim") is usually read "left to right", but if we replace it with "吉" ("jik"), then we know that it should be read "right to left".
Chinese, Japanese, and Korean are traditionally written vertically in columns from top to bottom and arranged from right to left, with each new column beginning to the left of the previous one. However, modern Chinese writing is generally read horizontally from left to right, like English.
In traditional Chinese writing, words are divided into characters, which are then grouped into lines. The order in which these elements are found on a page is called their "form". Forms are unique to each word and cannot be changed without changing the whole character. For example, imagine that we want to change the form of wang to match that of xu. We could do so by replacing it with an identical character, but because they are not identical characters, this would make them pronounce differently and thus mean different things. Instead, we must replace it with another character that has the same sound but a different meaning: nong.
Because forms are unique to each character, they can be known by their radical, a simple picture designed to help students learn the basic components of characters. There are several ways to identify radicals online, but none are perfect. Some websites simply show you a list of all the characters in order of frequency, and your job is to click on the correct one.