Price skimming involve setting a differn prices over time. For example, during the first relase the price will be set high for the high class, then the price will get lowered for the middle class, then finally the price will get lowered again for the working class.

This method/technique is good to use as it will exploit different areas of the market such as higher, middle, and lower/working class. Also you will be generating profit by creating a variety of choices for the consumer.