It can also signify 'fluctuation' or 'ups and downs' between two opposing states or emotions. You can use it when your mood swings from good to bad, or when prices are constantly changing.

It's widely used as an icon for the 'sort' function to organize data. It's also useful for visually showing the 'distance' or 'height difference' between two objects, and when talking about fashion, it can signify a top and bottom combination.