Linked from
The 11 pages that link to Riemann sum, each with the reason it gives.
CalculusBroader topic: Taking limits of these sums constructs the definite integral.
Partial sumRelated: Refining partitions produces successive finite sums that approach an integral.
Riemann integralRelated: Its limiting behavior defines the Riemann integral.
IntegralBroader topic: Its limit defines the Riemann integral.
Limits of integrationRelated: Its subdivision points span the interval set by the limits.