Nice article here that should help you out and to understand.
Why Confidence Is So Important (and How to Improve Yours)
how confidence play a major role in our life?
Dear Rathi Bala,
One more aspect in addition to the fine article Rooster found, is that the better you understand other people and your relationship/connection to them, the more peace you feel in your life.
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And that high quality of interpersonal understanding, along with acceptance, is something I would call confidence.