Qi Gong is at the core of Chinese Medicine. The practice typically involves moving meditation, coordinating slow flowing movement, deep rhythmic breathing, and calm meditative state of mind. There are many styles out there and some are more yang (hard) and some are more yin (soft). Some styles have particular focus. Over all most qi gong styles have a few things in common. Regulation of breath and coordination of that breath and body movements. Many people begin with the eight silken brocades as is it simple enough to learn and has a good over all energy workout.
Swimming Dragon qi gong has a focus on the movements of the spine and the flow of qi through it. This style is also focused on increasing the Kidney qi and is related to weight loss