Credibility is the quality of being trusted and believed. When someone has credibility, people take what they say seriously because they've proven themselves reliable and honest over time.

A news reporter builds credibility by checking facts carefully and reporting accurately. A scientist gains credibility through rigorous experiments and honest results. Your friend who always tells the truth has credibility, while someone who constantly exaggerates or makes things up loses it.

Credibility isn't automatic. You earn it through consistent actions: keeping promises, admitting mistakes, and demonstrating real knowledge about what you're talking about. If a student claims to be an expert chess player but loses every game, they lack credibility. But a student who studies hard and wins tournaments has earned credibility as a skilled player.

Once lost, credibility is hard to rebuild. If you make up a story and get caught, people will doubt you even when you're telling the truth later. That's why people with credibility guard their reputations carefully.