Review Article- Parasites: Introduction, Classification, Lifecycle and Relationship with their Hosts

Parasites are microorganism that need host to continue its lifecycle, some of them need direct life cycle while others needs indirect lifecycle. In this review article the researcher focus on things that related to types of parasites, as well as their lifecycles, and the type of the hosts, and how parasites affect the host and their relationship. The review comes over a wide range of years up to 2020, and the last published researches that are related to the topic of this review. The review discusses briefly the classification of the parasites and classified them into three main classes (groups), which are, Helminthes, Protozoa, and Arthropods. Eventually, the researchers came to a certain conclusions such as parasites are living species that needs host to continue its life cycle, there are many types of hosts depend upon the needs of parasites, there are more than eight million of parasites and their weight ranged from 25 microgram up to 70 grams.