Credibility is the quality of being credible, capacity or condition of being believed, just claim to credit, from the 1590s, from Medieval Latin credibilitas, from Latin credibilis.
Credibility is the cornerstone of communication. Build credibility in order to get others to listen to you otherwise your voice and ideas are noise. Listen carefully and patiently to obtain the facts while not arguing. Treat people as individuals based on those facts. Agree or disagree based on information and logic and do not promise more than you can deliver. Anticipate the effects of their speech and always accept responsibility for what you say and do.