Confidence Levels
So you have an interval and either your parameter is contained in the interval or not. We will know talk about assigning and changing the interval to get a better degree of confidence.
The Confidence Level of an interval estimate of a parameter is the probability that the interval estimate will contain the parameter, assuming that a large number of samples are selected and that the estimation process on the same parameter is repeated.
A Confidence Interval is a specific interval estimate of a parameter determined by using data obtained from a sample and by using the specific confidence level of the estimate.
.jpg "confidence intervals illustration")