Integrator Applet to find right, left, and general Riemann sum as well as upper and lower sums.

• Click on Options to bring up a dialog window for options
• For a definition of Riemann Sum, click here.
• For a definition of upper and lower sum, click here.
• For a definition of Riemann integral, click here.

Also check the general introduction to the Riemann integral as well as a discussion of various integration techniques.

You may also want to learn more about the Lebesgue integral, a generalization of the Riemann integral.