Yoga is a system of exercises that stretch and bend the body. It is also a system of meditation, breathing exercises, and relaxation. The word yoga comes from Sanskrit and means "union." It originally meant the joining together of the body and mind. Today, the word yoga is used more broadly to mean any spiritual practice. Yoga stretches and bends the body, but stretching and bending are not the same thing. Stretching is the act of stretching, while bending is the act of bending. Stretching is about lengthening and bending is about bending. It is often hard to see which stretches are done for stretching, and which for bending. The distinction between stretching and bending varies by culture. In Asian cultures, stretching is often done after exercising, to prepare the body for relaxing. In Western cultures, stretching is often done before exercising, to stretch and strengthen the body. Yoga focuses on stretching and bending the body. But stretching and bending are not the same thing, and practitioners of yoga often disagree about which stretches should be done before yoga and which after. Most people yoga instructors work with are new to yoga or haven't worked out in a while. Yoga instructors therefore tend to structure their classes around stretching and bending exercises. There are two kinds of stretches that can be called "yoga": static and dynamic. Static stretches are the stretching that is done as a warm-up before yoga. These stretches are done without moving, for the long muscles of the legs, arms, and back. Dynamic stretches are the stretching that is done during yoga. These stretches are done while moving, for the muscles in the lower part of the body and in the front of the legs.