Do you know how sometimes your clothes feel all rough and scratchy when you wear them? Well, fabric softener is something you can add to the washing machine to make your clothes feel nice and soft.
It's kind of like putting lotion on your skin to make it feel smooth.
Fabric softener has special ingredients in it that help to loosen up the fibers in your clothes and make them feel softer. It can also help to get rid of any static electricity that might make your clothes stick to you, which is kind of like when you rub a balloon on your head and your hair stands up.
Some people also like the way fabric softener makes their clothes smell really good.
But remember, you always need to ask a grown-up for help when using the washing machine and adding fabric softener.