Its hard to imagine all the signals we express & send out constantly & see them in others, if we're thinking too much. I've been learning body language since 1970s what they mean in people around. There's many book explaining BLS that began with 'The Silent Language' by Hall in '60s, & encounter groups encouraging expressing & reflecting instant observations & feedback to people open to it. Body language is openly or guarded expressions of our feeling, needs, attitudes, emotions, beliefs, goals, & position about anything in & around.This is the comprehensive book about BLS from many angles outside, relationships, expressing, hiding, emotions, goals, etc. It lists 108 ways & goals of BLS, seems a lifetime work now, i been learning with people for 40+ years, helping me understand what we feel & asking about it. One other book 'The Secret Language of Your Child' - by David Lewis shows video photos of kids BLS to help explain meanings. This book is encyclopedic with photos, jokes, lists, etc. Our BLS are common, continuous & even infinite in variety of our expressing inside out & reading with awareness, respect & empathy?! Seeing & learning BLS is essential to quick & deep communication, even if folks ain't aware of it.