Why does your dishwasher need salt?
What's the function of salt?
Salt is used to restore the functioning of the water softener. The water from your faucet contains lime and magnesium. Water with a lot of lime and magnesium is also known as 'hard' water. Every dishwasher contains a water softener to remove lime and magnesium from the water. If this doesn't happen correctly, your dishes will start showing white stains. Without salt, your water softener would become saturated after a while, and wouldn't function properly anymore.
Where do you put the salt?
The salt reservoir is on the bottom of your dishwasher. You can easily recognize the reservoir by its big dial. For optimal results, you should adjust the salt dosage to the hardness of the water at your home. If you don't do this, you'll either use too much salt, or you'll have issues with glass corrosion or white stains on your dishes. The amount of lime and magnesium in the water depends on where you live.
Which salt should you use?
After reading this, you might wonder if you can't just use table salt. You can't. There's a few important differences between dishwasher salt and table salt. Dishwasher salt has a coarse structure, which means it dissolves gradually and is used more evenly. On top of that, it often features anticoagulants to prevent blockages in the dishwasher. Other than that, dishwasher salt is very pure and designed not to leave any remains. Make sure to always use salt that's meant for use in dishwashers.