Kung Fu is the popular name of the collective Chinese martial arts. Literally the term kung fu means "hard work", "Skill earned through devotion and hard work", etc. The west have called kung fu as chinese boxing, the reason is easy to understand.
Kung fu styles are classified according to geographical location, themes, concepts etc. Geographically Kung fu is classified into two. Southern Kung fu styles and Northern Kung fu styles. Kung fu is further classified as External kungfu and Internal kung fu. Internal Kung fu mainly emphasis on using the chi power /Jin while the external kung fu uses the Li (the external energy). Even though it is seen rare, at an advanced stage, masters of both internal kung fu and external kung fu will be using their internal energy for attack and defense. Internal kung fu styles are often called soft kungfu and external kung fu styles are called hard kung fu styles. Tai chi chuan, Xing Yi Quan, Baguazhang, etc are the major 3 internal kung fu styles. Hung gar, wing chun, choy lee fut, etc are some of the well known external kung fu styles