A swab (10, 110) for a mop includes an outer casing (14) and an inner filling (20), the outer casing (14) being made of an absorbent material and enveloping the inner filling (20), and the inner filling (20) being made of an absorbent material, opposite major surfaces (16, 18) of the outer casing (14) being attached together though the inner filling (20) to form depressions (28) in the opposite major surfaces (16, 18) of the outer casing (14) and to limit movement of the inner filling (20) within the outer casing (14).