This document discusses confidence intervals, which provide a range of values that is likely to include an unknown population parameter based on a sample statistic. It defines confidence intervals and explains how they are calculated for means, proportions, odds ratios, and relative risks. Confidence intervals give more information than point estimates and allow for variability in samples. The width of the interval depends on the sample size, with larger samples having narrower intervals. Common confidence levels of 95% and 99% capture the percentage of intervals expected to contain the true population value.