Land Area Measurement and the units of measurement have historical links to agriculture. An acre was the land tillable in one day by a man with an ox drawn the plough. Traditional acres would be long, narrow strips to avoid the difficulty in turning the plough. For simple regular shapes as these or a rectangular field/site, measuring just requires two values, length and width.
The importance of being able to accurately measure land area for agriculture means livestock will be fed without causing damaging over grazing; Crops can be adequately irrigated without fear of wasting precious natural resources; Fertilization can be optimised to ensure the best return on investment and minimise ecosystem impact from excess run-off; And ultimately crop yield can be predicted.
However, today often a field/site will be an irregular shape that is not that simple to measure, manually calculate, nor even estimate its area. Fortunately, tools such as Area Measure take the uncertainty away by providing an accurate means to measure the land area.