Smile

Nothing conveys interest more easily and convincingly than a smile.  Babies instinctively return smiles at an early age. Strangers become a bit more familiar when smiles are exchanged.   Just thinking of friends and loved ones evokes smiles. 

A smile is a picture that can convey a thousand words and emotions - love, affection, familiarity, approachability, glee, joy, pride, acknowledgement, humor, connectivity...