toxins are basically poisons that get absorbed into your body through the environment or through food that you eat, and cause damage to your cells. some are also byproducts of normal metabolism. in large quantities they can be very harmful, but unless your health is already compromised because of a pre-existing illness you don't need to detox to get rid of them. the body will naturally flush them out through urine/tears/etc. it's important to have enough water though otherwise the body will have a harder time flushing them out, which will cause them to build up.