Shaolin Quan, also known as Shaolin Kung Fu, is among the oldest institutionalized styles of Chinese martial arts.
Like the usual system of Chinese martial arts, Shaolin combat methods are taught via forms. Some forms, like Small Hongquan, have just one section, and some, like Big Hongquan, have 3 or maybe more smaller parts, which every part can be considered a form itself. Some forms that are technically closely related are coupled together and are considered of the same style (sub-style is a better choice for the word), like Small and Big Hongquan, which altogether make the Shaolin Hongquan style; or Small and Big Paoquan, which make Shaolin Paoquan, Small and Big Tongbiquan, which make Shaolin Tongbiquan, Qi Xing and Chang Hu Xin Yi Men Quan, etc. There are some styles with one form, like Taizu Changquan, and styles that have been expanded into 5, 10, 13, 18, or even more forms. For example, Luohan 18 hands, which was originally one form, was expanded into 18 forms until the late Ming dynasty; Luohanquan, which originally just had small and big forms, has been expanded into a system of 18 forms called 18 Luohanquan; Shaolin big Hongquan nowadays has 13 forms; etc. Indeed, these styles are not complete or stand-alone, this is just a classification of different forms of Shaolin kung fu based on their technical contents.
Shaolin kung fu has more than hundreds of extant styles. There is recorded documentation of more than a thousand extant forms, which makes Shaolin the biggest school of martial art in the world. In the Qing dynasty (1644-1911), Shaolin monks chose 100 of the best styles of Shaolin kung fu. Then they shortlisted the 18 most famous of them. However, every lineage of Shaolin monks have always chosen their own styles. Every style teaches unique methods for fighting and keeping health via one or a few forms. To learn a complete system, Shaolin monks master a number of styles and weapons.