border-radius – with only one value, from 0% to 50% will affect a div. When using border-radius, more than one value may be used, to further customize the look of the div you're styling, but for the purpose of this visualization, we will be using only one value. When using border-radius, values other than percentages, such as pixels, ems, or rems, may be used, but for the purpose of this visualization, we will be using only percentages.