Which comes first, the posture or the alignment?
Why does alignment even matter?
In yoga, alignment is when the body is set up a specific way so there is no harm to it. It is different for everybody, and is a way to deepen your focus, your practice and your concentration.
Alignment in a yoga posture is just basic mapping of the body, a general scheme of where the body should be. Each body is unique in structure, so each yoga posture will be different for each person. Yoga should never hurt, but at times may feel a bit uncomfortable. Alignment is insurance that the body is and stays safe, especially when working deeper into the postures. Working in alignment means setting up a posture in a way that is supported evenly and naturally within the body. Usually working from the base up, you root to extend from connection of earth to extension into sky. In between the rooting and extension your body aligns as bones and muscles work with the next until continuously stretching. If there is compression or tension any where in the body than you usually are not in alignment. Same if you can't breathe fully or relax the neck, jaw, muscles of the face and shoulders, you are off or too far into something. As you work in alignment you not only building strength and flexibility in the body but by focusing on your bodies alignment you begin to improve your ability to concentrate as you practice keeping your mind focused and in control of one thing, your posture.
Align, for this is the growth of our practice, progress and peace.