Seasonality of food refers to the times of year when the harvest or the flavour of a given type food is at its peak. This is usually the time when the item is the cheapest and the freshest on the market. The food's peak harvest time usually coincides with when its flavour is at its best. There are some exceptions; an example being sweet potatoes which are best eaten quite a while after harvest. It also appeals to people who prefer a low carbon diet that reduces the greenhouse gas emissions resulting from food consumption (Food miles).