Statistics in connection with what is covariance?

Question Vijay Bank :? Statistics connection, which is the covariance pls provide sources if possible, please answer Reply to Michael K covariance is a measure of how much two variables vary together (as opposed to the variance, which measures how much a single variable varies). If two variables tend to vary together (ie, when one of them is more than the expected value, then the other variable tends to rise more

Ancova SPSS