Most Chinese characters consist of more than one component, i.e., 合體字[hé tǐ zì] compound characters. For example, the characters 柑([gān], mandarin orange) and 森（[sēn], thick forest） are made up of two (i.e., 木 and 甘) and three (i.e., three 木) components respectively.
Note that the organization of the components in the characters is not random. There are some principles operating to structure the components (i.e., the orthographic structure) so that the characters denote what they mean. Take the components 木([mù], tree), 甘([gān], sweet) and 火([huǒ], fire) as an example. As shown in Figure below, in a range of different characters, the components are arranged into different orthographic structures.
According to the way that the characters are made up of the components, compound characters can be divided into two categories: logical-aggregate characters and the more important semantic-phonetic characters.