Eight cups is equal to 2 quarts. Two quarts can also be called a half gallon. Converting measurements is important in many applications including cooking and construction.
When a recipe or measurement calls for one size measurement like 2 quarts, there may a need to convert it into a smaller measurement. The products that are being measured may not come in quart measurements, so knowing how many of a smaller or larger measurement goes into a quart makes measuring much easier. Getting instructions online means that they may originate somewhere that does not use the same type of measurement system, so the instructions may need to be converted to the correct measurement.