Excerpt for The Writing world Defined--A to Z: (www.stuartmarket.com)
Attributes of characters setting them apart from one another. In fiction, it is important the readers can see a specific difference between characters. One way to make those characters distinctly different is to give them a variety of tags. By tags, we mean such things as their manner of speech, the way they interact with the other characters, a favorite saying or cliche they repeat regularly, a tune they whistle or hum, perhaps a gesture such as pulling their earlobe, or twisting their hair around a finger. Tags can either endear a character to us or simply annoy us—and the reader. A good example of characters with very distinctive tags would be the various Charley Brown characters. We are never likely to get them mixed up. When writing a children’s book or a novel, you want each character to be so distinctly different the reader can usually tell who's talking without being told. Character tags can also include the character's choice of clothing or hair style. If you are able to describe a favorite storybook or novel character from memory, that description will include the character's various tags. In creating your own characters, if you are not able to describe them accurately, it is usually because you have not endowed him or her with those unique tags. To learn more about character tags, go to: http://www.dailywritingtips.com/character-tags-in-fiction.