Echelon form, also called row echelon form, is a form of a matrix having the following characteristics:
1. All zero rows are at the bottom of the matrix.
2. The leading entry of each nonzero row after the first occurs to the right of the leading entry of the previous row.
3. All entries below a leading entry are zero.
Some conventions additionally require each leading entry to be 1. Gaussian elimination produces a row-echelon form, which is generally not unique. Strengthening the conditions on the leading entries gives reduced row echelon form.
