Parasites are the living organism that take their nutrition by other living organism without killing them. This mode of nutrition is known as parasitic mode of nutrition. They are the part of the the heterotrophic nutrition all the organism that are parasites are confirm heterotrophs.
Example- A host may be a plant or an animal parasite in this mode, nutrition is observed in several fungi, bacteria and in a few plants like cuscuta and some animals like plasmodium, roundworm these causes several diseases like malaria.