Confidence is one of the words we throw around without knowing what the heck we are talking about.
In fact, it probably best approached by the symptoms of what’s there when we are NOT confident.
According to wikipedia, confidence is this
con·fi·dence
the feeling or belief that one can rely on someone or something; firm trust.
“we had every confidence in the staff”
synonyms: trust, belief, faith, credence, conviction
“I have little confidence in these figures”
antonyms: skepticism, distrust
the state of feeling certain about the truth of something.
“it is not possible to say with confidence how much of the increase in sea levels is due to melting glaciers”
a feeling of self-assurance arising from one’s appreciation of one’s own abilities or qualities.
“she’s brimming with confidence”
synonyms: self-assurance, self-confidence, self-possession, assertiveness;