With some basic understanding of Chinese characters under your belt, let's now get a little more technical by talking about radicals. But please, no Abbey Hoffman jokes.
Radicals are the 214 character elements (189 in the simplified system) around which the Chinese writing system is organized. Some of these elements can stand alone as individual characters; others function only when combined with additional character elements.
The important point, however, is that every Chinese character either is a radical or contains a radical. This makes using radicals the most sensible basis for organizing entries in a Chinese dictionary...which happens to be just how it's done.
Using a Chinese-English Dictionary
To look up the meaning of a character in a Chinese-English dictionary, you must first know which element in it is the radical. At first this may require some guesswork. Most radicals appear on the left side of the character, but you may also find them on the top, on the bottom, or in the middle. Looking at the following characters, though, a person who is literate in Chinese will know that 
(rén) is the radical in each.
Suppose you see the character "
" for the first time and want to look up its meaning and pronunciation. Here's what you do:
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First, go to the front of the dictionary wher you'll find a table listing all radicals in groups by the number of strokes in each. That is, all the one-stroke radicals are listed first, then the two-stroke radicals, and so on. Since
(rén) contains two strokes, look in the two-stroke section to find that has been assigned number 19. -
Next, go to a table immediately following the first, find the section labeled "#19" and there find a complete list of characters containing the radical
(rén). Scan the list for "" and see beside it xìn. -
Now use the half of the dictionary organized according to pinyin spelling to look up. Find the right entry by making sure the character "
" is beside it, and read that (xìn) means letter, the kind you send by mail.
The process has a few steps, but looking up the meaning of a new Chinese character is not as difficult as you might guess.
