Hölder's Inequality is a fundamental result in mathematics that provides a way to estimate the integral or sum of the product of two functions. It states that for any two measurable functions and their respective exponents, the integral of their product is less than or equal to the product of their individual norms. This is particularly useful in analysis and probability theory. The inequality is named after the mathematician Otto Hölder, who introduced it in the 19th century. It is often used in various fields, including functional analysis and measure theory, to establish bounds and prove other important results.