Pictogram-Ideogram-Logogram

Pictogram

A pictogram, also called a pictogramme or pictograph is an ideogram that conveys its meaning through its pictorial resemblance to a physical object. Pictographs are often used in writing and graphic systems in which the characters are to considerable extent pictorial in appearence.Pictography is a form of writing which uses representational, pictorial drawings.It is a basis of cuneiform and to some extent, hieroglyphic writing, which also uses drawings as phonetic letters or determinative rhymes.

   

(Water,rabbit,deer pictographs on a replica of an Aztec Stone of the Sun)

Ideogram

An ideogram or ideograph is a graphic symbol that represents an idea or concept. Some ideograms are comprehensible only by familiarity with prior convention;others convey their meaning through pictorial resemblance to a physical object, and thus may also be referred to as pictograms.

Logogram

A logogram or logograph is a single grapheme which represents a word or a morpheme (a meaningful unit of language). This stands in contrast to other writing systems, such as alphabets, where each symbol (letter) primarily represents a sound or a combination of sounds.

References

http://en.wikipedia.org/wiki/Pictogram

http://en.wikipedia.org/wiki/Logogram

http://en.wikipedia.org/wiki/Ideogram