The number of items that can be washed in a dishwasher depends on the size and model of the dishwasher and the size of the dishes that are being washed. It is best to refer to the owner's manual for specifics on each dishwasher's capacity.
When loading a dishwasher, dishes should only be pre-rinsed if they are not being washed right away. All plastic or lightweight items should be secured so that they do not flip over. To ensure that all items in the dishwasher can be reached by the spray arms and water jets, stacking items is not advised.