How to "load" a rail?

[ChesterMcCheese]

As we know, our PSU rails are loaded when we make a device that runs on a rail do work. Now PSU testers don't test using a computer - they use equipment to load the rails. My question is - how is this done? I assume they increase the current to a rail, since the rail voltages stay constant (or are supposed to) until this current hits the maximum rated current. Specifically, how is this done? And how are maximum load tests done - do they feed the maximum rated amps to all the rails, multiply the current by the voltage of the rail, sum them to find whether this equals the max rated power, and see whether it blows or not?

[Cap'n Pedro]

"Load" is the ammount of power being drawn (used up). And what, kids, uses up electricity? A resistor! A big ass one. That's how it's done, usually, anyway.

[larrymoencurly]

For a serious load you need something like lots of 5-20W resistors (my 380W rat's nest), long lengths of nichrome wire, or 12V lightbulbs (sealed beams for cars are good).