The written Chinese language is considered to be the writing system that has been continuously used for the longest period of time. Something interesting about the Chinese language is that even though the pronunciation of the characters has changed in various regions, the characters themselves have remained relatively the same throughout the Chinese speaking communities. Therefore, even if two people speak different dialects of Chinese (such as Cantonese and Mandarin, for example), they can still write and communicate with each other.
The earliest known written form of Chinese is called the Oracle Bone Script, named so because it was mainly written on bone fragments or turtle shells in the process of divination in Ancient China. A number of these characters were pictograms, pictures that would represent other objects. Over the centuries, these characters were written differently and eventually reached the point of where the previous pictograms of the Oracle Bone Script were no longer easily recognized as such.
There are some attached images of Chinese characters with this story, three Oracle Bone Script characters and their Traditional equivalents. Looking closely, one can perhaps see the relation between the two characters and how the Oracle Bone Script character had evolved into the current Traditional character.
Today, there are two different systems of printing Chinese characters, those being the Traditional and the Simplified. (There are various forms and styles of hand writing Chinese characters, one of which is the Seal Script referred to above.)
The Simplified system as it is today was developed by the People's Republic of China to helped improve literacy among the Chinese population. Essentially reducing the number of strokes needed to write some of the more complex characters (an example is given in the pictures attached to this story), the Simplified system does greatly improve the ability to read certain Chinese characters. The system is in use in Mainland China, Singapore, the United Nations and Malaysia.
Hong Kong, Macau and Taiwan use traditional characters. Traditional characters are generally used in Chinese communities elsewhere in the world, though simplified characters are becoming more popular in those communities. Traditional characters have their roots from a standardization of Chinese characters about 1500 years ago.