Kanji are often made up of discrete, identifiable components called radicals. Radicals appear in kanji for a variety of reasons. Some indicate meaning, some indicate the way in which the character should be pronounced, and have been simplified into existing radicals from more complex stroke patterns, or have gradually lost their association over time.
運転 | うんてん | unten | driving |
Both of the kanji in this compound contain 車 as a radical. The radical itself represents a spoked cartwheel; this directly relates to the meaning of the word.
Kanji dictionaries tend to arrange kanji by radical. By memorizing common radicals, it becomes much easier to remember how kanji are written.