Confidence level is an indicator of certainty of the result of a statistical measurements. It is expressed as the percentage and signifies the probability that the measurement we made can be repeated with the same result. For example it can be stated as being 95% certain that the experiment you conducted is repeatable and that it will always yield the same result. Confidence level should not be confused with significance, though. Significance tells us the probability that the result we observed is not the product of chance.