A Hankel matrix is a special type of matrix in which each ascending skew-diagonal from left to right is constant. This means that the elements of the matrix are determined by a sequence of numbers, where each element in the first column and the first row defines the rest of the matrix. Hankel matrices are often used in signal processing and control theory. These matrices are named after the German mathematician Hermann Hankel. They have unique properties that make them useful in various mathematical applications, including polynomial interpolation and system identification. The structure of a Hankel matrix allows for efficient computation and analysis in these fields.