Radicals are common components in Chinese characters. Some indicate pronunciation and some suggest meaning. E.g.
Some radicals themselves may be single-component characters, such as 女 and 马.
However, some are not single-component characters, but may be combined with other components to form characters. E.g. 氵(shuǐ – water)- together with 工 (gōng – work) forms 江 (jiāng – river).
In order to understand and write Chinese characters correctly, it is important to make sense of the radicals.
Radicals can be placed on the left, right, top, bottom and outside of a Chinese character.
Images courtesy of Chineasy.