When it works correctly, a dishwasher should thoroughly coat your dishes in a soapy solution of warm water and detergent, followed by rinsing them off fresh water. Unfortunately, however, they don't always work like this, and something a problem mechanism or improper use will cause them to not dry on the last cycle. As you can expect, this forces you to hand dry each and every dish you want to wash, which is a time-consuming process. If you want to take back control of your dishwasher, you must identify the reason why it isn't drying dishes like it should.
Use Rinse Agent
A lot of woners overlook the importance of using rinse aid when doing a load of dishes. After all, it's not like its detergent, so what's the point of it? Well, rinse aid is used to help clean the remaining food particles and water stains off the dishes during the last cycle. Depending on the type of dishwasher you're using, there's usually a small compartment where you add the rinse aid. Just pop the lid, fill it up to the specified line, and turn on your dishwasher. Not only will rinse aid give you cleaner dishes, but it will also help dry them as well. You can pick up bottles of rinse aid for about $7-$10 bucks from most general home goods stores.
Dishwashers have built-in heating elements used to heat the water for both the washing and drying cycle. If this element is broken or isn't working as it should, chances are your dishes won't get dry. The easiest way to tell if this is the problem is to feel your dishes immediately after washing them. If they're still cold and wet, then you know it's the heating element. On the other hand, if your dishes are hot to the touch, it's working just fine and the problem is likely somewhere else.
Common sense should tell you that overloading your dishwasher may also cause it to not dry your dishes as it should. This is simply because some of the dishes and plates block the warm water and steam from reaching others; therefore, they aren't able to try. Take caution when loading your dishwasher and try to leave plenty of space between them. In addition to drying your dishes easier, loading the dishwasher with less dishes will also reduce the chances of dishes breaking during the process.