A mathematical computation involving a set of values rather than a single value. Aggregate functions are often used in databases and spreadsheets, and include the mean or sum of a set of numbers. The calculation performed by an aggregate function returns a single value from multiple values.
The use of computers has revolutionized the way that calculations are performed, allowing aggregate functions to produce results very quickly. In addition, aggregate functions can handle ever larger and more complex data sets, which has allowed the construction of aggregate supply and demand functions.