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human
Difference between covariance and correlation, variance and standard deviation

Might  be a fundamentally basic question but I am confused since I could not find one place where I could find the difference between covariance, correlation, variance and standard deviation. 

An example to understand their purpose would be of great help. 

Thanks a ton!!!
gpt
Covariance: Measures how strongly two variables tend to move in the same direction, depends on the scale of the data so it's hard to interpret but it often has mathematical uses in derivations and stuff.

Correlation: Standardized version of covariance so it's between -1 and 1, which makes it much more interpretable.

Variance: Covariance of a variable with itself, so it just measures how much variation there is within one variable.

Standard deviation: Square root of the variance, again aids interpretability because the SD has the same units as the variable that it is the SD of while variance is in squared units.