Vinyasa can be described as a linked series of postures. Typically in a vinyasa one strings the postures on the breath like beads, and the flow will repeat a series between longer holds at specific points in the chain.
With any posture in yoga there are two questions: How to do it safely and effectively, but also Why to do it at all. When I was very young and trying out yoga poses I saw on Lilias, or in books and so on, I would see a cool looking pose and try to mimic it. It was all about the pose. But when you do that you start to realize that some poses feel good, and that they might feel good at particular times of the day, or after other activities. That is why I tell my students “Think of the posture as a tool, rather than as a goal”.
One way to begin strength training is to buy a set of dumbbells and start moving them around. Over time, bit by bit, we come to understand that we can get better benefits by being more precise: we start organizing our lifting into sets and reps, measuring the amount of weight lifted, planning out which days to train, and so on. What a good trainer understands though, is that there is a step missing here.
If we were to find ourselves in a weightless, gravity free environment balance practice would be meaningless. Balance of our bodies assumes a frame of reference within which we are blancing. I think for yoga this is one of the most interesting aspects of practicing balance. In yoga one of the first journeys we take is an inward journey.... learning to listen carefully to our bodies, to connect our bodies to our thoughts and our breath. But a journey only inward is inherently sterile.