Model organism
A model organism is one which is studied to further our understanding of biological processes. Typical characteristics of model organisms include developing to maturity rapidly, the ability to be easily manipulated and produce a large number of offspring. Model organisms if possible need to have cheap sources, short lives and to be non-pathogenic.
Some widely used model organisms are S. cerervisiae, S. pombe, Drosophilia, C. elegans, Zebrafish and Mice.