Microbiology is the study of microscopic organisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). It encompasses pure and applied microbiology. Pure microbiology includes virology, mycology, parasitology and bacteriology. As an application of microbiology, medical microbiology is often introduced with medical principles of immunology as microbiology and immunology. The course also provides the basic concepts of microbiology.