Confidence Intervals, Histograms, & Distributions
A confidence interval (CI) indicates that you are confident to a certain degree that the observed value of your metric would fall within the given range.
The probability that the observed metric would take on different values is encoded in a probability distribution. A histogram visualizes a distribution with the likelihood of observing certain values (y-axis) against those values (x-axis).
Guesstimate can translate your intuitive CI to some common distributions. This is covered in the 'Modeling' section.