An interest rate is the percentage of interest relative to the principal. It is either what lenders charge borrowers or what is earned from deposit accounts.| Investopedia
A stock, also known as a share, is a tradable claim to fractional ownership of the corporation that issued it.| Investopedia
Standard deviation is a statistic measuring the dispersion of a dataset relative to its mean. It is calculated as the square root of the variance. Learn how it's used.| Investopedia