Percentage points refer to a measure of change or difference in percentage values. It is calculated by subtracting the old value from the new value and then dividing that result by the original value. For example, if there was a 5% increase in sales from last year, we can say it's an increase of 5 percentage points because the current sales have increased by 5%, which means they are now at 105%. So, percentage points provide more clarity and specificity to changes or differences expressed as percentages.