👉 A column in mathematics refers to a subset of a matrix or vector space. A column is a submatrix that spans the entire rowspace (or nullspace) of a given matrix. This means that it contains all the entries from the original matrix, and each entry is associated with a unique row index. For example, consider a 3x2 matrix: ``` A = | 1 0 | | 2 3 | ``` The column vector `v`