Most people probably know that Chinese writing uses figures, usually called characters, that do not represent the pronunciation at all. The average college graduate in China knows 6000 or more characters, but if you know 3000, you can usually read a typical Chinese newspaper.
What most people don't know, however, is that the Chinese Communist government simplified many characters. The result is that there are now two sets of characters--the traditional characters and the simplified characters. The people in mainland China use the simplified characters, while Chinese in Taiwan, Hong Kong, Singapore, the U. S. and other Chinese communities used the traditional characters.
If you study Chinese in the U. S., especially by self-study, as I did, you will almost necessarily have to study the traditional characters, because available books and newspapers come from the outlying Chinese communities.
When you arrive in Hong Kong, you will encounter the Cantonese dialect much more frequently than Mandarin. Cantonese uses the traditional characters, but often with different meanings and pronunciations. So you can read printed material, but you cannot pronounce it. When you arrive in Beijing, then, you will be able to pronounce the words as they should be pronounced in Mandarin, but you won't be able to read many or most of the characters. It takes several more months to learn the quota of simplified characters that you will need to read mainland material.
Instead of learning 3000 characters then, you may have to learn 5000, with 1000 or so remaining the same, or varying only slightly. Once you have been in China about a year, if you are assiduous, you will be able to read both traditional and simplified characters. But as soon as you leave China, you begin to forget. Their acquisition is by no means a permanent fixture of your mind. The upside is that, if you have forgotten a lot over a period of years, it comes back more easily than if you were starting entirely anew.
Here is a link with a few specimens:
Examples of Traditional and Simplified Characters
Photo Credit: http://www.flickr.com/photos/mikeknowles/111446529/
