Different kinds of designs may be used in many life sciences; one may needs some optimal constraints on the design of interest. The proper meaning of 'optimal' depends on the situation, and can include: most effective, minimum variance, minimum bias, etc. Optimal design is an essential topic that deserves special attention from many researchers who are interesting in data analysis in several fields in our life such as: dynamic, kinetic, toxicity, marketing and engineering fields. In the light of the value of this subject, this paper is devoted to introduce a concise survey on the optimality criteria and its classifications. Moreover, the relationships among several optimality criteria will be derived. Finally, all the criteria and their relations are summarized in a graph to be more noticeable