Downward facing dog engages your whole being. It calms your nervous system and works on overall flexible strength. It decompresses your spine, tones and strengthens your arms, opens the arches of your feet, sculpts and lengthens your thighs, and is an amazing shoulder opener.
Alignment of Downward Facing Dog:
You should look like an inverted V.
Contract and activate your quadriceps. Press your thighbones back behind you.
Pull your hips back and tilt your tailbone up.
Pull your belly toward your spine.
Press your arms down and forward. Drop your shoulder blades down your back, externally rotating, palms should be flat pressing your mat forward, and pushing your chest toward your thighs.
Spread your fingers and place weight into your knuckles, not your wrists. Press down through the knuckles of index fingers, not letting the weight fall off to the pinky sides of hands.
Gaze between your feet. Breathe.