Hand wave has very basic purpose that makes us social by exhibiting disarmed and friendly state. By holding open palms with stretched fingers visible to others silently conveys "Feel safe from me! I'm not holding any arm or weapon". Waving hand isn't as formal like

. Ritual of hand shake's like treaty of ensuring mutual disarmament and willingness to connect whereas hand wave goes beyond formality. It has become social and casual practice of showing off openness, friendliness and harmless intentions. More affectionate and intimate hand wave silently says "

Don't forget me...

", "

I care for you...

" or "

Come again

...".