Vinyasa, also called flow because of the smooth way that the poses run together, is one of the most popular contemporary styles of yoga. It’s a broad classification that encompasses many different types of yoga, including Ashtanga and power yoga.
In contemporary yoga parlance, vinyasa stands in opposition to hatha. Hatha classes tend to focus on one pose at a time with rest in between. In contrast, flow classes string poses together to make a sequence. The sequence may be fixed, as in Ashtanga in which the poses are always done in the same order, but most of the time vinyasa teachers have the discretion to arrange the progression of poses in their own ways.
In vinyasa yoga, each movement is synchronized to a breath. The breath is given primacy, acting as an anchor as you move from one pose to the next. A cat-cow stretch is an example of a very simple vinyasa. The spine is arched on an inhale and rounded on an exhale. A sun salutation sequence is a more complex vinyasa. Each movement in the series is cued by an inhalation or an exhalation of the breath.