Pranayama is the meditative style of breathing performed when doing yoga.
Pranayama and meditation  are  similar  but different. The best way to think about pranayama is that it is a gateway toward the meditative state.Essentially, pranayama is consciously controlling the breath while performing yoga.If you have ever taken a yoga class, you will have heard your yoga instructor describing how to breathe while exercising (inhaling in Cobra / exhaling in Downward Dog and so on). This is pranayama.