Correlation coefficients measure how two things are related. If one thing changes, the other might change too, either in the same way (positive correlation) or the opposite way (negative correlation). The Pearson correlation is used for data that follow a normal pattern, while the Spearman correlation is used for data that don't. Both types of correlation range from -1 to +1, with 0 meaning no relationship and closer to 1 or -1 meaning a strong relationship. Tests can show if the relationship is significant. This tutorial helps people understand how to use and interpret correlation coefficients.