what is a pivot column

In linear algebra, a pivot column is a column in a matrix that contains a pivot, which is the first nonzero entry of a row in row-echelon form. The columns in which pivots appear are called pivot columns. The pivots of a matrix are simply the leading entries, which are the first nonzero entries of each row in row-echelon form. The pivot columns are the columns in which the pivots appear. In summary, a pivot column is a column in a matrix that contains a pivot, which is the first nonzero entry of a row in row-echelon form, and the columns in which pivots appear are called pivot columns.